Publications Repository - Gdańsk University of Technology

Page settings

polski
Publications Repository
Gdańsk University of Technology

Show publications from the year

Recent items

  • Computationally-efficient design optimisation of antennas by accelerated gradient search with sensitivity and design change monitoring
    • Anna Pietrenko-Dąbrowska
    • Sławomir Kozieł
    2020 Full text IET Microwaves Antennas & Propagation

    Electromagnetic (EM) simulation tools are of primary importance in the design of contemporary antennas. The necessity of accurate performance evaluation of complex structures is a reason why the final tuning of antenna dimensions, aimed at improvement of electrical and field characteristics, needs to be based on EM analysis. Design automation is highly desirable and can be achieved by coupling EM solvers with numerical optimisation routines. Unfortunately, its computational overhead may be impractically high for conventional algorithms. This study proposes an efficient gradient search algorithm with numerical derivatives. The acceleration of the optimisation process is obtained by means of the two mechanisms developed to suppress some of finite-differentiation-based updates of the antenna response sensitivities that involve monitoring and quantifying the gradient changes as well as design relocation between the consecutive algorithm iterations. Both methods considerably reduce the need for finite differentiation, leading to significant computational savings. At the same time, excellent reliability and repeatability is maintained, which is demonstrated through statistics over multiple algorithm runs with random initial designs. The proposed approach is validated using a benchmark set of wideband antennas. The proposed algorithm is competitive to both the reference trust-region algorithm as well as its recently reported accelerated versions.

  • Computations of the least number of periodic points of smooth boundary-preserving self-maps of simply-connected manifolds
    • Grzegorz Graff
    • Jerzy Jezierski
    • Adrian Myszkowski
    2020 Topological Methods in Nonlinear Analysis

    Let $r$ be an odd natural number, $M$ a compact simply-connected smooth manifold, $\dim M\geq 4$, such that its boundary $\partial M$ is also simply-connected. We consider $f$, a $C^1$ self-maps of $M$, preserving $\partial M$. In [G. Graff and J. Jezierski, Geom. Dedicata 187 (2017), 241-258] the smooth Nielsen type periodic number $D_r(f;M,\partial M)$ was defined and proved to be equal to the minimal number of $r$-periodic points for all maps preserving $\partial M$ and $C^1$-homotopic to $f$. In this paper we demonstrate a purely combinatorial method of calculation of the invariant and illustrate it in various cases.

  • Computed tomography indicators of cerebral microperfusion improve long term after carotid stenting in symptomatic patients
    • Paweł J. Winklewski
    • Mariusz Kaszubowski
    • Grzegorz Halena
    • Agnieszka Sabisz
    • K Chojnicki
    • Jaroslaw Dzierzanowski
    • Maciej Piskunowicz
    • N. Kurhaluk
    • Edyta Szurowska
    • Arkadiusz Szarmach
    2020 Full text Acta Biochimica Polonica

    OBJECTIVES: We tested the hypothesis that computed tomography (CT) perfusion markers of cerebral microcirculation would improve 36 months after internal carotid artery stenting for symptomatic carotid stenosis while results obtained 6-8 weeks after the stenting procedure would yield a predictive value. METHODS: We recruited consecutive eligible patients with >70% symptomatic carotid stenosis with a complete circle of Willis and normal vertebral arteries to the observational cohort study. We detected changes in the cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP) and permeability surface area-product (PS) before and after carotid stenting. We have also compared the absolute differences in the ipsilateral and contralateral CT perfusion markers before and after stenting. The search for regression models of "36 months after stenting" results was based on a stepwise analysis with bidirectional elimination method. RESULTS: A total of 34 patients completed the 36 months follow-up (15 females, mean age of 69.68±S.D. 7.61 years). At 36 months after stenting, the absolute values for CT perfusion markers had improved: CBF (ipsilateral: +7.76%, contralateral: +0.95%); CBV (ipsilateral: +5.13%, contralateral: +3.00%); MTT (ipsilateral: -12.90%; contralateral: -5.63%); TTP (ipsilateral: -2.10%, contralateral: -4.73%) and PS (ipsilateral: -35.21%, contralateral: -35.45%). MTT assessed 6-8 weeks after stenting predicted the MTT value 36 months after stenting (ipsilateral: R2=0.867, contralateral R2=0.688). CONCLUSIONS: We have demonstrated improvements in CT perfusion markers of cerebral microcirculation health that persist for at least 3 years after carotid artery stenting in symptomatic patients. MTT assessed 6-8 weeks after stenting yields a predictive value.

  • Concentration of Potentially Bioactive Compounds in Italian Extra Virgin Olive Oils from Various Sources by Using LC-MS and Multivariate Data Analysis
    • Anna Różańska
    • Marina Russo
    • Francesco Cacciola
    • Fabio Salafia
    • Żaneta Polkowska
    • Paola Dugo
    • Luigi Mondello
    2020 Full text Foods

    High quality extra virgin olive oils represent an optimal source of nutraceuticals. The European Union (EU) is the world’s leading olive oil producer, with the Mediterranean region as the main contributor. This makes the EU the greatest exporter and consumer of olive oil in the world. However, small olive oil producers also contribute to olive oil production. Beneficial effects on human health of extra virgin olive oil are well known, and these can be correlated to the presence of vitamin E and phenols. Together with the origin of the olives, extraction technology can influence the chemical composition of extra virgin olive oil. The aim of this study was to investigate the concentration of potentially bioactive compounds in Italian extra virgin olive oils from various sources. For this purpose, vitamin E and phenolic fractions were characterized using high-performance liquid chromatography (HPLC) coupled with fluorescence, photodiode array and mass spectrometry detection in fifty samples of oil pressed at industrial plants and sixty-six samples of oil produced in low-scale mills. Multivariate statistical data analysis was used to determine the applicability of selected phenolic compounds as potential quality indicators of extra virgin olive oils.

  • Concept of a swirling diffuser in batch blending tanks
    • Wojciech Artichowicz
    • Jerzy Sawicki
    2020 Full text CHINESE JOURNAL OF CHEMICAL ENGINEERING

    The mixing of two or more components belongs to the category of the most common unit operations, both in technology and in nature. One particular version is homogenization (blending), the effectivity of which is strongly related to the blending time. Among many differentiated individual solutions of mixing systems used in blenders, one should distinguish the class of agitators with diffusers. An analysis of the character of the velocity field during a blending chamber operation leads to the conclusion that it would be of avail to outfit a straight diffuser with different setup of elbows. In consequence, the vertical direction of the inflowing fluid stream would be changed into the horizontal direction of the outflowing stream, which should intensify the blending process. The concept has been verified experimentally, making use of the tracer methodology. The obtained results confirmed the theoretical conclusion, that the blending time for the swirling-diffuser was shorter than for the classical straight one.

  • Concrete Compressive Strength Under Changing Environmental Conditions During Placement Processes
    • Andrzej Ambroziak
    • Patryk Ziółkowski
    2020 Full text Materials

    The technological process of concrete production consists of several parts, including concrete mix design, concrete mix production, transportation of fresh concrete mix to a construction site, placement in concrete framework, and curing. Proper execution of these steps provides good quality concrete. Some factors can disturb the technological process, mainly temperature and excessive precipitation. Changing daily temperature and rainfall during fabrication, transportation, and placement can shape not only the properties of the concrete mix but also the compressive strength of hardened concrete. In this paper, we tried to answer the question of how temperature and precipitation affect concrete production. The scope of this study was to determine the change of compressive strength of the hardened concrete in a specific period for selected concrete mix recipes, taking into account changing daily temperature and precipitation magnitude. The investigated concrete mixes concrete compressive strength beyond that of the concrete grade, termed "concrete superstrength.” This concrete post limiting behaviour of concrete is also discussed.

  • CONCRETE MIX DESIGN USING SIMPLE EQUATIONS
    • Hakim Abdelgader
    • Ramadan Suleiman
    • Abdalla Adam
    • Jamal Khatib
    2020 Full text BAU Journal - Science and Technology

    The behaviour of concrete, whether fresh or har dened, depends basically on the beha viour of its components and the r elationship between them, ther efore, obtaining a concr ete with cer tain pr operties depends fundamentally on the concr ete mix design. Concr ete mix design gener ally includes two main steps: 1-Selection of the main components suitable for the concr ete (cement, aggr egate, water , and additiv es); 2-Determination of mor e economical mix r atios t o fulfil the workability , str ength and efficiency requirements. Curr ently, ther e ar e many international methods locally appr oved for mix designs. The y are all r elated t o each other , the y giv e r elatively the same quantities of the mix components and the y are all capable of pr oviding a good concr ete mix. It is impor tant t o consider that these methods giv e approximate quantities which should be check ed b y experimental mix es in or der t o obtain r esults suitable for the r equirements of the local envir onment and local materials. The A CI and BS methods ar e the most commonly used. Both of these methods depend on gr aphs and standar d tables deriv ed fr om pr evious research experience and actual concr ete pr oduction as well as studies of the pr operties of the materials used. This paper illustr ates a new appr oach for concr ete mix design named as: “Double Coating Method”, which is curr ently used in some r esearch centers in the r epublic of P oland and was r ecently applied in the laboratories of the Civil Engineering Depar tments in the Univ ersities of T ripoli and Benghazi in Lib ya. This paper describes experiment in which 24 mixtur es wer e used t o assess the usefulness of this technique for problem of pr oportioning concr ete mixtur es in gener

  • Concrete-filled FRP tubular members in marine and bridge structures
    • Marcin Abramski
    2020

    Concrete core of the concrete-filled tubes (CFTs) with circular cross-section is in the case of an axial compression subjected to a spatial state of compressive stresses. This state leads to enhancement in the concrete strength. The enhancement is utilized in Eurocode 4 design procedures for CFSTs (i.e. CFTs with tube made of steel). The structural design of CFFTs (i.e. CFTs with tube made of Fibre Reinforced Polymer - FRP) is normalized in LFRD Guide Specifications released by AASHTO in 2012. The mathematical model of confined concrete adopted in these design guidelines has also regard to the concrete strength enhancement. The differences between the both models of triaxially compressed concrete are discussed in the paper. The latter model was used in an author’s computer program developed to calculate the load-carrying capacity of 15 CFFT columns which were previously experimentally investigated in the axial and eccentric compression. The calculated and experimentally obtained capacities are compared. The auctorial program predicted the columns load-carrying capacity with a safety margin of 33% on average.

  • Conductivity, structure, and thermodynamics of Y2Ti2O7–Y3NbO7 solid solutions
    • Piotr Winiarz
    • Aleksandra Mielewczyk-Gryń
    • Kristina Lilova
    • Sebastian Wachowski
    • Tamilarasan Subramani
    • Mykola Abramchuk
    • Ewa Dzik
    • Alexandra Navrotsky
    • Maria Gazda
    2020 Full text DALTON TRANSACTIONS

    The defect fluorite yttrium niobate Y3NbO7 and pyrochlore yttrium titanate Y2Ti2O7 solid solutions have been synthesized via a solid state synthesis route. The resulting stoichiometry of the oxides is Y2+xTi2−2xNbxO7, where x = 0 to x = 1. All of the samples were single-phase; however, for those with a predominant fluorite phase, a small amount of additional pyrochlore phase was detected. The volume of the solid solution unit cells linearly increases with increase in yttrium niobate content. The water uptake increases with (x) and the protonic defect concentration reaches almost 4.5 × 10−3 mol mol−1 at 300 °C. The calculated enthalpy of formation from oxides suggests strong stability for all of the compositions, with the values of enthalpy ranging from −84.6 to −114.3 kJ mol−1 . The total conductivity does not have a visible dependence on Y3NbO7 content. For each compound, the total conductivity is higher in wet air. Interestingly, for samples where x < 0.5, the ratio of conductivity in hydrogen to air increases with increasing temperature, while for x > 0.5, the trend is the opposite.

  • Conjugates of Ciprofloxacin and Levofloxacin with Cell-Penetrating Peptide Exhibit Antifungal Activity and Mammalian Cytotoxicity
    • Natalia Ptaszyńska
    • Katarzyna Gucwa
    • Katarzyna Olkiewicz
    • Mateusz Heldt
    • Marcin Serocki
    • Anna Stupak
    • Dorota Martynow
    • Dawid Dębowski
    • Agata Gitlin-Domagalska
    • Jan Lica
    • Anna Łęgowska
    • Sławomir Milewski
    • Krzysztof Rolka
    2020 Full text INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES

    Seven conjugates composed of well-known fluoroquinolone antibacterial agents, ciprofloxacin (CIP) or levofloxacin (LVX), and a cell-penetrating peptide transportan 10 (TP10-NH2) were synthesised. The drugs were covalently bound to the peptide via an amide bond, methylenecarbonyl moiety, or a disulfide bridge. Conjugation of fluoroquinolones to TP10-NH2 resulted in congeners demonstrating antifungal in vitro activity against human pathogenic yeasts of the Candida genus (MICs in the 6.25 – 100 μM range), whereas the components were poorly active. The antibacterial in vitro activity of most of the conjugates was lower than the activity of CIP or LVX, but the antibacterial effect of CIP-S-S-TP10-NH2 was similar to the mother fluoroquinolone. Additionally, for two representative CIP and LVX conjugates, a rapid bactericidal effect was shown. Compared to fluoroquinolones, TP10-NH2 and the majority of its conjugates generated a relatively low level of reactive oxygen species (ROS) in human embryonic kidney cells (HEK293) and human myeloid leukemia cells (HL-60). The conjugates exhibited cytotoxicity against three cell lines, HEK293, HepG2 (human liver cancer cell line), and LLC-PK1 (old male pig kidney cells), with IC50 values in the 10 – 100 μM range and hemolytic activity. The mammalian toxicity was due to the intrinsic cytoplasmic membrane disruption activity of TP10-NH2 since fluoroquinolones themselves were not cytotoxic. Nevertheless, the selectivity index values of the conjugates, both for the bacteria and human pathogenic yeasts, remained favourable.

  • Considerations about the applicability of the Reynolds equation for analyzing high-speed near field levitation phenomena
    • Noël Brunetière
    • Michał Wodtke
    2020 Full text JOURNAL OF SOUND AND VIBRATION

    equation for analyzing near field levitation (NFL) phenomena. Two separate approaches were developed, experimentally verified, and applied to meet the research objective. One was based on the Reynolds equation and the other was based on general conservation equations for fluid flow solved using computational fluid dynamic (CFD). Comparing the calculation results revealed that, for certain operating conditions, differences in the predicted system parameters appear. It was proven that both the Reynolds and Helmholtz numbers define border operating conditions for the applicability of the Reynolds equation to analyze NFL problems.

  • Constitutive Modelling of Knitted Abdominal Implants in Numerical Simulations of Repaired Hernia Mechanics
    • Agnieszka Tomaszewska
    • Daniil Reznikov
    • Czesław Szymczak
    • Izabela Lubowiecka
    2020 Full text

    The paper presents a numerical approach to describe mechanical behavior of anisotropic textile material, which is a selected abdominal prosthesis. Two constitutive nonlinear concepts are compared. In the first one the material is considered composed from two families of threads (dense net model) and in the second one the material is homogeneous but anisotropic (as proposed by Gassel, Ogden, Holzapfel). Parameters of both models are identified based on experimental tensile tests (uni-axial and bi-axial, simple and cyclic). The constitutive relations are applied in numerical membrane model of the prosthesis applied in the abdominal wall. Its mechanical responses to the pressure loading has been compared, also to deflection experimentally observed in physical model of the operated hernia of the same geometry. The authors find that both constitutive models properly describe the implant’s mechanics, but further studies are needed to possibly approach the outcome of hyperelastic anisotropic model to experimental results obtained for synthetic knit mesh

  • Constructing a Dataset of Speech Recordingswith Lombard Effect
    • Dawid Weber
    • Szymon Zaporowski
    • Daniel Korzekwa
    2020

    Thepurpose of therecordings was to create a speech corpus based on the ISLEdataset, extended with video and Lombard speech. Selected from a set of 165sentences, 10, evaluatedas having thehighest possibility to occur in the context ofthe Lombard effect,were repeated in the presence of the so-called babble speech to obtain Lombard speech features. Altogether,15speakers were recorded, and speech parameterswere calculated and analyzed. First, a brief summary of the research related to the Lombard effect is given. Then, therecording studiocharacteristicsand the equipment utilizedfor recordings areshown.Examples of analyses are included,concerning both non-Lombard and Lombard speech. Finally, a recapitulation of experiments performedalong with further researchplans is given.The link to the data is also provided.

  • Consumerism in Poland – a fact or a myth?
    • Anna Drapińska
    2020

    Purpose Consumerism, understood as excessive consumption, poses a vital problem in the world, and requires taking appropriate steps and actions in individual countries depending on the extent and nature of this phenomenon. The purpose of this paper is to examine the phenomenon of consumerism in Poland, with partial reference to other EU countries and to answer the question whether there is consumerism as such in Poland. Design/methodology/approach Data from secondary sources were used for the purpose of the paper. The study is based on statistical data analysis (Eurostat, Polish Statistical Main Office) and surveys of national experts, institutions and research agencies. The time span of the data observed extended from 2010 to 2018. The applied method can be defined as a descriptive statistics method with elements of quantitative analysis. Findings The study shows that the phenomenon of consumerism in Poland is not yet developed to the extent comparable to Western European countries. With the basic needs of the majority of average Polish households consuming the major part of their income, combined with the necessity to rationalize spending, which is forced by social and economic situation, consumers are more inclined to reasonably manage their resources. Polish consumers are still trying to catch up and meet their needs at a level similar to that in highly developed countries. Nevertheless, one can observe some symptoms of consumerist behaviour, e.g. spending on pleasure and entertainment prevails over saving, buying unnecessary things, or pleasure shopping. Originality/value Until now, the subject of consumerism in Poland was tackled very rarely and in a fragmentary way. No answer was given to the question whether there is consumerism in Poland and what is the level of its advancement. This paper is an attempt to identify this phenomenon based on available secondary sources. In addition it has been shown that statistics indicating the fifth place of Poland in Europe in terms of food waste are 'best estimates' mainly based on 2006 data from Eurostat and unfortunately no data were available from Poland.

  • Contact force network evolution in active earth pressure state of granular materials: photo‑elastic tests and DEM
    • Leśniewska Danuta
    • Michał Nitka
    • Andrzej Tejchman-Konarzewski
    • M. Pietrzak
    2020 Full text GRANULAR MATTER

    Artykuł omawia ewolucję sieci sił kontaktowych w materiałach granulowanych podczas quasi-statycznego stanu aktywnego. Doświadczenia foto sprężyste zostały wykonane dla kulek szklanych. Doświadczenia zostały symulowane stosując metodę elementów dyskretnych (DEM). Model DEM prawidłowo przewidział strukturę sił kontaktowych i ich wielkość, lokalizację odkształceń oraz obszary zmian fazowych.

  • Contamination of Arctic Lakes with Persistent Toxic PAH Substances in the NW Part of Wedel Jarlsberg Land (Bellsund, Svalbard)
    • Sara Lehmann-konera
    • Ruman Marek
    • Łukasz Franczak
    • Żaneta Polkowska
    2020 Full text Water

    The expansion of glacier‐free areas in polar regions favours the appearance of lakes in the non‐glaciated parts of glacier basins. This paper presents the differentiation of organic compound concentrations in fifty‐four Arctic lakes collected in four locations (Logne Valley, in the vicinity of the Scott, Renard and Antonia glaciers). We cover meteorological measurements, chemical analysis of sixteen dioxin‐like compounds (Polycyclic Aromatic Hydrocarbons (PAHs)), formaldehyde (HCHO), sum parameters of phenolic compounds (Σphenols) and dissolved organic carbon (DOC). The most contaminated with PAH compounds were lakes exposed to the influence of the Greenland Sea (Logne Valley lakes) and to the prevailing winds (Scott and Renard lakes). Interpretation of the PAH compounds results allowed for identification of pyrogenic sources as the main sources of PAH compounds in the year 2012. The highest levels of HCHO and Σphenols were observed for the Scott lakes, while the highest DOC levels were noted in Antonia lakes.

  • Contemporary architecture within the context of architectural education
    • Agnieszka Malinowska
    • Karolina Taraszkiewicz
    2020 Full text World Transactions on Engineering and Technology Education

    Analysed in this article are the diploma projects of students of architecture in European countries. The aim was to examine how students approach an important issue related to sustainable development, i.e. the integration of newly designed architecture into the existing historical, cultural and natural context. The rational use and protection of the environment requires the skilful shaping of urbanised space. Many changes in the surrounding space, which result from the work of architectural engineers, have a huge impact on the quality of this space. Special emphasis was placed on creating methods for educating future professional engineer architects to understand the need for the proper coexistence of newly designed urban and architectural solutions within the existing historical, cultural and natural context, as well as having the skills to create such solutions.

  • Contextual ontology for tonality assessment
    • Wojciech Waloszek
    • Nina Rizun
    2020 Full text Procedia Computer Science

    classification tasks. The discussion focuses on two important research hypotheses: (1) whether it is possible to construct such an ontology from a corpus of textual document, and (2) whether it is possible and beneficial to use inferencing from this ontology to support the process of sentiment classification. To support the first hypothesis we present a method of extraction of hierarchy of contexts from a set of textual documents and encoding this hierarchy into a multi-level contextual ontology. To support the second hypothesis, we present a method of reasoning from the ontology, and results of experimental verification, which show that use of this reasoning method can increase accuracy of sentiment classification for longer text documents

  • Control of nonlinear and linearized model of self-balancing electric motorcycle
    • Adam Wonia
    • Michał Wonia
    • Robert Piotrowski
    2020 Full text

    Self-Balancing Electric Motorcycle (SBEM) is a dynamic and nonlinear electro-mechanical system. In this paper, the process of mathematical modelling and line-arization of SBEM is presented. The model of the control system in Matlab envi-ronment is implemented. The control system using the PID controller is designed. The operation of particular structures of the PID controller on the simulation model is compared. Due to simulation research, the most appropriate structure and parameters of the PID controller are chosen.

  • Convenient and Efficient Synthesis of Functionalized 2-Sulfenylindoles
    • Justyna Doroszuk
    • Mateusz Musiejuk
    • Bartosz Jędrzejewski
    • Juliusz Walczak
    • Dariusz Witt
    2020 Full text Materials

    A simple, efficient, and practical sulfenylation at the C2 position of N-tosylindoles under mild conditions was developed. The designed transformation is based on the reaction of N-tosylindoles with BuLi and S-alkyl, and S-aryl phosphorodithioates or thiotosylates to produce 2-sulfenylindoles in moderate to high yields. The presence of additional hydroxy, carboxy, or amino functionalities did not disturb the formation of products

  • Convergence of Monte Carlo algorithm for solving integral equations in light scattering simulations
    • Maciej Kraszewski
    • Jerzy Pluciński
    2020 Full text OPTICA APPLICATA

    The light scattering process can be modeled mathematically using the Fredholm integral equation. This equation is usually solved after its discretization and transformation into the system of algebraic equations. Volume integral equations can be also solved without discretization using the Monte Carlo (MC) algorithm, but its application to the light scattering simulations has not been sufficiently studied. Here we present implementation of this algorithm for one- and three-dimensional light scattering computations and discuss its applicability in this field. We show that the MC algorithm can provide valid and accurate results but, due to its convergence properties, it might be difficult to apply for problems with large volumes or refractive indices of scattering objects.

  • Coordination complexes of Mn(II), Co(II), Ni(II), Zn(II) and Cd(II) with histaminol – Crystal structures and formation constants in aqueous solution
    • Piotr Maślewski
    • Dariusz Wyrzykowski
    • Weronika Kentner
    • Anna Ciborska
    • Anna Dołęga
    2020 POLYHEDRON

    Stability constants were determined for a series of coordination complexes of Mn(II), Co(II), Ni(II), Zn(II) and Cd(II) with histaminol in aqueous solution. The tendency of histaminol to form chelate complexes has been confirmed by the isolation of several complex species in the monocrystalline form and determination of their molecular structures.

  • Copolymerization of Styrene and Pentadecylphenylmethacrylate (PDPMA): Synthesis, Characterization, Thermomechanical and Adhesion Properties
    • Tomy Muringayil
    • Sumi Murali Nair
    • Suresh Kattimuttathu Ittara
    • Józef Haponiuk
    • Sabu Thomas
    2020 Full text Polymers

    The copolymerization of styrene (St) with a bioderived monomer, pentadecylphenylmethacrylate (PDPMA), via atom transfer radical polymerization (ATRP) was studied in this work.The copolymerization reactivity ratio was calculated using the composition data obtained from1HNMR spectroscopy, applying Kelen-Tudos and Finemann-Ross methods. The reactivity ratio of styrene (r1=0.93) and PDPMA (r2=0.05) suggested random copolymerization of the two monomers with alternation. The copolymerization conversion increased with increasing PDPMA concentrationof the feed, upto 70 wt % PDPMA, but decreased thereafter. The molecular weight determined by gel permeation chromatography was lower than the theoretical values and the polydispersity increased from 1.32 to 2.19, with increasing PDPMA content in the feed. The influence of styrene content on the glass transition and thermal decomposition behavior of the copolymers was studied bydifferential scanning calorimetry (DSC) and thermogravimetric analysis, respectively. Morphologicalcharacterization by transmission electron microscopy (TEM) revealed a phase separated soft core-hardshell type structure. The complex viscosity and adhesion properties like peel strength and lap shear strength of the copolymer on different substrates increased with increasing styrene content

  • Corporate Entrepreneurship: A Literature Review and Future Research Perspectives
    • Magdalena Popowska
    2020 Full text International Journal of Contemporary Management

    Background. Nowadays, corporate entrepreneurship (CE) is perceived as an essential approach to boost the innovation and creativity within existing organizations for achieving higher opportunities in the market. This paper examines this concept, which has been largely discussed in the Anglo-Saxon world over the last thirty years. Like for many other phenomena, also in case of CE, this discussion has provided numerous conceptualizations, and consequently, there is not one unique definition of CE. In this respect, the search for an appropriate basis for understanding and describing the phenomenon of CE engenders a challenging issue for entrepreneurship researchers. Research aims. This paper aims at creating a large platform for understanding the concept of CE by means of a clarification effort through the review of the most important papers in this field and identification of the existing research gaps. Methodology. Systematic literature survey is the applied methodology. EBSCO and Taylor & Francis database were used as a source for the sampling process. Key findings. The analysis does acknowledge the need for more qualitative and rigorous research in this field and brings several recommendations for the future studies. The main conclusions also do urge for a more diversified research in terms of the sectors discussed, as the biggest gap identified is in the services sector. There is also a need for a more structured classification of the measures, depending on the real research focus: CE antecedents or outcomes.

  • Corporate social responsibility practices incomes and outcomes: Stakeholders' pressure, culture, employee commitment, corporate reputation, and brand performance. A Polish–German cross‐country study
    • Rafał Kowalczyk
    • Wioleta Kucharska
    2020 Full text Corporate Social Responsibility and Environmental Management

    This study aims to compare employee perception of corporate social responsibility (CSR) practice incomes and outcomes in the construction industry in Poland and Germany. It proposes a model that examines the influence of stakeholder pressure, culture, and CSR practices on company brand performance, reputation, and employee identification. The findings suggest that the structure of relationships varies for project‐managed construction companies in a developed country such as Germany and a rapidly transformed Poland. The structural equation modeling method was adopted to analyze the differences between the structures of relationships using AMOS and Process software. The key finding reveals that stakeholder pressure can lead to consistent CSR‐oriented system in the business environment. This study was first conducted in 2018 and then replicated in 2019 to confirm the results with 1,674 cases. The novelty essence is the comparison of the Polish and German structure of CSR practice incomes and outcomes related to employee perception.

  • Correction of determined coordinates of railway tracks in mobile satellite measurements
    • Andrzej Wilk
    • Cezary Specht
    • Krzysztof Karwowski
    • Władysław Koc
    • Jacek Skibicki
    • Krzysztof Czaplewski
    • Piotr Chrostowski
    • Paweł Dąbrowski
    • Sławomir Grulkowski
    • Sławomir Judek
    • Mariusz Specht
    • Jacek Szmagliński
    2020 Full text Diagnostyka

    This article examines one of the basic issues related to the technique of mobile satellite measurements in railway tracks. This problem concerns the correction of the determined coordinates of the track centerline. The need to perform this operation results from the GNSS receivers positioning at a certain height above the level of the existing track axis, leading to longitudinal and lateral shifts of antennas. The key problem here is the determination of the local horizontal coordinate system in each measured position. For the analysis, the authors defined the directional baseline vector of the measuring platform on the basis of positions given by two satellite antennas, positioned over the pivots of its bogies. This work presents the procedure for determining the corrections values

  • Correlation between partial inhibition of hydrogen evolution using thiourea and catalytic activity of AB5-type hydrogen storage alloy towards borohydride electrooxidation
    • Małgorzata Graś
    • Jarosław Wojciechowski
    • Katarzyna Lota
    • Tomasz Buchwald
    • Jacek Ryl
    • Grzegorz Lota
    2020 Full text JOURNAL OF ALLOYS AND COMPOUNDS

    Direct borohydride fuel cells (DBFCs) are devices which directly convert the chemical energy stored in the borohydride ion and oxidant into electrical energy as a result of redox reactions. Unfortunately, a significant amount of fuel is lost as a result of the undesirable hydrolysis reaction. The selection of an efficient borohydride hydrolysis inhibitor requires detailed knowledge regarding the interaction mechanism between the inhibitor molecule and electrode surface. In this study, various amounts of thiourea additives (0.011–1.600 mM) were tested to select the best fuel composition for DBFC application. When AB5-type anode was used, only partial inhibition of sodium borohydride hydrolysis was a desirable phenomenon. Partially released hydrogen results in the improvement of catalytic properties of the alloy. The addition of 0.016 mM thiourea does not inhibit the oxidation of borohydride, on the contrary, it increases the practical capacity from 27% to 41% of the theoretical value. Moreover, we indicate that the addition of thiourea prevents corrosion as well as degradation of the electrode surface. Pressure measurements confirmed the effectiveness of thiourea in relation to hydrogen evolution, while X-ray photoelectron spectroscopy and Raman spectroscopy revealed that the electrode surface was not poisoned.

  • Correlations between the wear of car brake friction materials and airborne wear particle emissions
    • Wojciech Tarasiuk
    • Karol Golak
    • Yurii Tsybrii
    • Oleksii Nosko
    2020 Full text WEAR

    Airborne wear particles emitted from transport vehicle brakes are one of the main sources of toxic metals in inhalable particulate matter. Prediction of wear particle emissions may become more accurate if the relationship between the wear and particle emission characteristics is known. An experimental study was performed to investigate proportional correlations between the mass wear, 0.01–0.42 μm particle emission measured by a NanoScan SMPS Nanoparticle Sizer (SMPS) and 0.3–10 μm particle emission measured by an Optical Particle Sizer (OPS). Several car brake low-metallic materials in the form of pin samples were tested against steel disc samples at different values of the contact pressure and sliding velocity. The pin-on-disc friction pair was placed in a clean chamber to eliminate external particle sources. The obtained results suggest a strong proportional correlation between the disc sample wear and pin sample wear. OPS and SMPS particle concentrations were also revealed to strongly correlate between each other. By contrast, the disc sample wear exhibited weak correlations with the particle concentrations for most of the materials.

  • Corrosion hazards and inhibitor protection in the seawater injection system on the Baltic sea rig
    • Kinga Domańska
    • Piotr Igliński
    • Juliusz Orlikowski
    • Krzysztof Żakowski
    • Kazimierz Darowicki
    2020 Full text International Journal of Corrosion and Scale Inhibition

    Oil extraction efficiency in LOTOS Petrobaltic Company is increased by means of injection of seawater into an oilfield aquifer, which is implemented on the Baltic Beta rig, operating on the Baltic Sea. Operational experience has shown a significant degree of corrosion aggressiveness in the injected water, which necessitates frequent repairs of the seawater injection installation. Evaluation of the corrosion phenomena is crucial for rig platforms due to extremely high renovation costs and a negative impact on injected water quality. Chemical and microbiological analyses of seawater treated in the technological process have been carried out. Actions to estimate the corrosion risk in the installation and the estimated corrosion rates measured using an automated monitoring system are presented in this work. Monitoring of the corrosion rate conducted alongside measurements of the physicochemical properties of water allowed to identify the corrosion mechanisms of stainless steel in a seawater environment. Additionally, it became possible to assess the impact of the chlorine and carbon dioxide content on the corrosion rate, and to analyze the effectiveness of the corrosion inhibitor. The effectiveness of two types of commercial corrosion inhibitors has been estimated during different conditions.

  • Corrugated Sheeting as a Member of a Shear Panel Under Repeated Load—Experimental Test
    • Natalia Korcz-Konkol
    • Piotr Iwicki
    2020 Full text Materials

    In stressed-skin design, the cladding stiffening effect on structures is taken into account. However, the “traditional” design is more usual, wherein this effect is neglected. Even if the diaphragm actions are not regarded, in particular cases such as big sheds (and others), the parasitic (unwanted) stressed-skin action may occur with the result of leakage or even failure. The structures of this kind have already been built. Thus, an important question arises: How can one assess them if there is a need to correct or redesign them? What kind of non-destructive approach can be used to achieve that? Experimental tests of small-scale shear panels made of trapezoidal sheeting were designed in order to observe the behaviour of the diaphragm under increasing and repeated load. The tests were oriented toward force–displacement relations and strains in selected areas of the sheeting. The results revealed nonlinear, hysteretic force–displacement behaviour of the panel and the occurrence of the persistent deflections and stresses which remain even after the unloading. The relation among the stresses, force–displacement paths and modes of failure can be potentially used in monitoring systems of existing buildings in terms of parasitic stressed-skin action.

  • Cost-Efficient Bi-Layer Modeling of Antenna Input Characteristics Using Gradient Kriging Surrogates
    • Anna Pietrenko-Dąbrowska
    • Sławomir Kozieł
    • Muath Al-hasan
    2020 Full text IEEE Access

    Over the recent years, surrogate modeling has been playing an increasing role in the design of antenna structures. The main incentive is to mitigate the issues related to high cost of electromagnetic (EM)-based procedures. Among the various techniques, approximation surrogates are the most popular ones due to their flexibility and easy access. Notwithstanding, data-driven modeling of antenna characteristics is associated with serious practical issues, the primary one being the curse of dimensionality, particularly troublesome due to typically high nonlinearity of antenna responses. This limits applicability of conventional surrogates to simple structures described by a few parameters within narrow ranges thereof, which is grossly insufficient from the point of view of design utility. Many of these issues can be alleviated by the recently proposed constrained modeling techniques that restrict the surrogate domain to regions containing high-quality designs with respect to the relevant performance figures, which are identified using the pre-optimized reference designs at an extra computational effort. This paper proposes a methodology based on gradient-enhanced kriging (GEK). It enables a considerable reduction of the number of reference points required to construct the inverse surrogate (employed in surrogate model definition) by incorporating the sensitivity data into the nested kriging framework. Using two antenna examples, it is demonstrated to yield significant savings in terms of the surrogate model setup cost as compared to both conventional modeling methods and the original nested kriging.

  • Cost‐efficient performance‐driven modelling of multi‐band antennas by variable‐fidelity electromagnetic simulations and customized space mapping
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2020 INTERNATIONAL JOURNAL OF NUMERICAL MODELLING-ELECTRONIC NETWORKS DEVICES AND FIELDS

    Electromagnetic (EM) simulations have become an indispensable tool in the design of contemporary antennas. EM‐driven tasks, for example, parametric optimization, entail considerable computational efforts, which may be reduced by employing surrogate models. Yet, data‐driven modelling of antenna characteristics is largely hindered by the curse of dimensionality. This may be addressed using the recently reported domain‐confinement techniques, especially the nested‐kriging framework, which permits rendering of reliable surrogates over wide ranges of antenna parameters while greatly reducing the computational overhead of training data acquisition. Focused on modelling of multi‐band antennas, this paper attempts to reduce the cost of surrogate construction even further by incorporating variable‐fidelity simulations into the nested kriging. The principal challenge being design‐dependent frequency shifts between the models of various fidelities is handled through the development of a customized frequency scaling and output space mapping. Validation is carried out using a dual‐band dipole antenna modeled over broad ranges of operating conditions. A small training data set is sufficient to secure the predictive power comparable to that of the nested kriging model set up using solely high‐fidelity data, and by far exceeding the accuracy of conventional surrogates. Application examples for antenna optimization and experimental verification of the selected designs are also provided.

  • Cost-Efficient Surrogate Modeling of High-Frequency Structures Using Nested Kriging with Automated Adjustment of Model Domain Lateral Dimensions
    • Anna Pietrenko-Dąbrowska
    • Sławomir Kozieł
    2020 Full text AEU-INTERNATIONAL JOURNAL OF ELECTRONICS AND COMMUNICATIONS

    Surrogate models are becoming popular tools of choice in mitigating issues related to the excessive cost of electromagnetic (EM)-driven design of high-frequency structures. Among available techniques, approximation modeling is by far the most popular due to its versatility. In particular, the surrogates are exclusively based on the sampled simulation data with no need to involve engineering insight or problem-specific knowledge. Notwithstanding, a typically high nonlinearity of system outputs and the curse of dimensionality limit the applicability of conventional methods to relatively simple structures described by a few parameters within narrow ranges thereof. A recently reported nested kriging alleviates these difficulties from the perspective of an appropriate definition of the model domain. By focusing the modeling process on the region containing design that are optimized for the selected performance figures, it enables the construction of reliable surrogates over wide ranges of geometry/material parameters and operating conditions, both at a practically acceptable computational cost. The relative model domain thickness (i.e., its lateral-to-tangential size), determines the trade-off between the surrogate region of coverage and its predictive power, the former being essential for practical applications of the model, especially design optimization. This paper proposes a simple and computationally efficient procedure for automatic selection of the thickness parameter, which, in the original version of the method, was to be selected by the user. The importance of this aspect of the modeling process and the benefits of the proposed approach are demonstrated using a dual-band dipole antenna and miniaturized microstrip coupler.

  • Could thermal imaging supplement surface electromyography measurements for skeletal muscles?
    • Bartłomiej Zagrodny
    • Wiktoria Wojnicz
    • Michał Ludwicki
    • Jan Awrejcewicz
    2020 Full text IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT

    Abstract—(1) Background: The aim of this study is to present the results of experiments in which surface electromyography (sEMG) and thermal imaging were used to assess muscle activation during gait and to verify the hypothesis that there is a relationship in the case of low fatigue level between sEMG measured muscle activation, assessed in the frequency domain, and thermal factors calculated as minimum, maximum, kurtosis, mean, median and mode from the area of interest. (2) Methods: Comparison of activity calculated from the recorded sEMG data for rectus femoris, biceps femoris, tibialis anterior and gastrocnemius medialis with thermal data obtained from the infrared vision. (3) Results: Data of fourteen healthy volunteers obtained during 10 minutes of treadmill gait are presented and analyzed. The analysis revealed statistically significant: linear correlations for rectus femoris (five moderate relationships) and gastrocnemius medialis (one good relationship); moderate nonlinear correlations for all examined muscles. Also, a detailed protocol for precise, repeatable thermal examination is presented. (4) Conclusions: Estimated moderate linear and non-linear correlations between thermal and electromyographic parameters are found for low level of muscle fatigue, which suggests that the presented method is useful in the analysis of muscle activation with the use of a thermal imaging as a complement to sEMG.

  • Coupled evolution of preferential paths for force and damage in the pre-failure regime in disordered and heterogeneous, quasi-brittle granular materials.
    • A. Tordesillas
    • S. Kahagalage
    • C. Ras
    • Michał Nitka
    • Andrzej Tejchman-Konarzewski
    2020 Full text Frontiers in Materials

    Metoda elementów dyskretnych (DEM) została wykorzystana do symulacji betonu poddanego jednoosiowemu rozciąganiu. Beton modelowano jako materiał losową heterogeniczy 2/3-fazowy, złożony z cząstek kruszywa, matrycy cementowej i stref przejściowych międzyfazowej. Odkryto dowody na zoptymalizowaną transmisję siły, scharakteryzowaną przez dwa nowe wzorce, które przewidują i wyjaśniają sprzężoną ewolucję ścieżki siły i uszkodzenia od poziomu mikrostrukturalnego do poziomu makroskopowego. Pierwszy obejmuje możliwie najkrótsze ścieżki transmisji, które mogą przenosić siłę globalną. Ścieżki te przewidują łańcuchy sił rozciągających. Drugi wzór to wąskie gardło przepływu, ścieżka po zoptymalizowanej drodze, która jest podatna na zatory i pojawia się tam gdzie jest makro-rysa. Kooperacyjna ewolucja preferencyjnych ścieżki dla uszkodzeń i siły rzuca światło na to, dlaczego miejsca o najwyższym stężeniu naprężeń i uszkodzenia w początkowych stadiach obszaru przed zniszczeniem nie dostarczają realistycznego wskaźnika ostatecznego położenia makro-rysy.

  • COVID-19 and digital deprivation in Poland
    • Marta Kuc-Czarnecka
    2020 Full text Oeconomia Copernicana

    Research background: The problem of digital deprivation is already known, but the COVID-19 pandemic has highlighted its negative consequences. A global change in the way of life, work and socialisation resulting from the epidemic has indicated that a basic level of digital integration is becoming necessary. During the lockdown, people were forced to use ICTs to adapt to a rapidly changing reality. Current experience with coronavirus pandemic shows that the transition to these extraordinary circumstances is not smooth. The inability to rapid conversion to the online world (due to a lack of skills or technical capabilities) significantly reduces professional mobility, hinders access to public services, and in the case of children, exposes them to the risk of remaining outside the remote education system. Purpose of the article: This research paper is addressing new issues of the impact of the COVID-19 pandemic on deepening and increasing the severity of e-exclusion. The goal of the paper is to indicate territorial areas in Poland, which are particularly vulnerable to digital deprivation due to infrastructural deficiencies. Methods: Raster data regarding landform, combined with vector data regarding population density and type of buildings as well as the location of BTS stations are used in so-called modelling overland paths (GIS method) to indicate areas vulnerable to the infrastructural digital divide. Findings & Value added: The research showed that 4% of Poles remain outside the Internet coverage, and additional ten percent of them out of the reach of the Internet, allowing efficient remote work or learning. The research indicated that digital 'accessibility gap' is underestimated. E-exclusion has become a pressing issue and requires urgent system solutions, in case of future lockdowns.

  • CROSS SECTIONS CALCULATIONS FOR ELECTRON SCATTERING FROM RHODANINE AND CYANOACETIC ACID
    • Bożena Żywicka
    • Paweł Możejko
    2020 Full text PUBLICATIONS OF THE ASTRONOMICAL OBSERVATORY OF BELGRADE

    Cross sections for electron-impact ionization and for elastic electron scattering for rhodanine (C3H3NOS2) and cyanoacetic acid (C3H3NO2) have been calculated in wide impinging electron energy range.

  • Crystal Growth, Structure, and Magnetism of the 2D Spin 1/2 Triangular Lattice Material Rb3Yb(PO4)2
    • Shu Guo
    • Ruidan Zhong
    • Karolina Górnicka
    • Tomasz Klimczuk
    • Robert J. Cava
    2020 CHEMISTRY OF MATERIALS

    The single-crystal growth, crystal structure, heat capacity, and anisotropic magnetization characterization of Rb3Yb- (PO4)2, a Yb-based triangular lattice material, are presented. Single-crystal X-ray diffraction shows that Rb3Yb(PO4)2 exhibits [Yb(PO4)]∞ layers, with the Yb in an ordered plane of equilateral triangles. One phosphate group oxygen that is not a near neighbor of the magnetic Yb displays positional disorder. The temperaturedependent magnetization is anisotropic, with no long-range magnetic ordering observed for temperatures down to 50 mK. The low temperature heat capacity in the presence of an applied magnetic field is fitted very well by a Schottky anomaly with a linear magnetic-field-dependent gap between the ground and excited state energies. At 1.8 K, no magnetic transitions are seen for applied fields up to 90 kOe. Our results suggest that Rb3Yb(PO4)2 is a good candidate for displaying frustrated magnetism at low temperatures.

  • Crystal structure and physical properties of AePd1-xP1+x (Ae = Ca, Sr)
    • Joanna Blawat
    • Zuzanna Ryżyńska
    • Tomasz Klimczuk
    • Weiwei Xie
    • Jin Rongying
    2020 Materials Today Communications

    We report the discovery of two new compounds AePd1-xP1+x (Ae = Ca, Sr) crystallized in different hexagonal structures. Single crystals of AePd1-xP1+x (Ae = Ca, Sr) are obtained using the Bi-flux method. Crystallographic analysis by both powder and single crystal X-ray diffraction shows that CaPd1-xP1+x crystallizes in a non-centrosymmetric hexagonal structure with the space group P-6m2 (No.187) and lattice parameters a = b = 4.0391(9) Å and c = 4.1026(9) Å, while SrPd1-xP1+x forms a centrosymmetric hexagonal structure with the space group P63/mmc (No. 194) and lattice parameters a = b = 4.102(2) Å and c = 8.713(4) Å. In both compounds, Pd and P atoms mix in the honeycomb layer with a higher amount of P. The electronic structure calculations show that the mixture of Pd and P atoms in the honeycomb network is critical to stabilize the crystal structures. AePd1-xP1+x (Ae = Ca, Sr) are diamagnetic metals confirmed by the magnetic susceptibility, electrical resistivity and specific heat.

  • Current Status, Barriers and Development Perspectives for Circular Bioeconomy in Polish South Baltic Area
    • Dariusz Mikielewicz
    • Paweł Dąbrowski
    • Roksana Bochniak
    • Aleksandra Gołąbek
    2020 Full text Sustainability

    The following article presents the current legal situation in Poland as well as in the European Union. Data on biomass production in the Polish South Baltic area were analyzed, along with an indication of the key sectors for the development of bioeconomy. Presentation of the current state of biomass management was made and areas necessary for development were indicated to facilitate the sustainable management of biomass and waste generated during its processing. Differences between regions in the Polish South Baltic Area show how an individual approach in each of these areas is required. During the analysis, the most important barrier to the implementation of the circular economy was distinguished, which is the lack of an appropriate legal framework. This is to be changed by the Circular Economy Road Map, adopted in 2019.

  • Current trends in analytical strategies for determination of polybrominated diphenyl ethers (PBDEs) in samples with different matrix compositions – Part 1.: Screening of new developments in sample preparation
    • Monika Śmiełowska
    • Bożena Zabiegała
    2020 TRAC-TRENDS IN ANALYTICAL CHEMISTRY

    Polybrominated diphenyl ethers (PBDEs) are ubiquitous compounds in the environment. Restrictions on the use of PBDEs introduced at the beginning of the 21st century have not eliminated these highly persistent and bioaccumulative compounds from the environment. Despite many existing regulations to control and phase out, extensive research on PBDEs is still necessary to fully evaluate the hazard their create to the environment. In most samples PBDEs occur at very low concentrations, which make analysis of these compounds difficult. The choice of an effective technique for the extraction of analytes that allows for their separation from interfering substances and the matrix is an important part of the analytical procedure for PBDEs determination. The paper presents a review of the literature on challenges related to the analysis of PBDEs in samples of different matrix compositions, the latest solutions used for sample preparation and future trends in sample preparation for PBDE analysis.

  • Current trends in analytical strategies for the determination of polybrominated diphenyl ethers (PBDEs) in samples with different matrix compositions – Part 2: New approaches to PBDEs determination
    • Monika Śmiełowska
    • Bożena Zabiegała
    2020 TRAC-TRENDS IN ANALYTICAL CHEMISTRY

    Herein, we review the latest technical solutions for polybrominated diphenyl ethers (PBDEs) determination in samples with different matrix compositions, largely focusing on gas chromatography but also presenting some liquid chromatography–based solutions. Moreover, we discuss the use of diverse sample injection techniques while considering the advantages and disadvantages of each injection system in the context of PBDEs analysis. For instance, the use of modern injection systems allowing the injection of larger-than-standard volumes may increase determination sensitivity, reduce analyte discrimination, and avoid thermally induced debromination. Attention is also paid to the possibility of using high-thermal-resistance chromatographic columns to decrease the extent of column bleeding and obtain better working conditions for the applied detection techniques, e.g., by increasing the signal-to-noise ratio. The importance of detector selection is emphasised, and data on the latest PBDE detection techniques are provided. Finally, we discuss the idea of using other devices in screening analysis to suspect the presence of PBDEs, mainly in polymer samples. As a future trends, we have provided data on the possibility of using modern solutions, including sensors.

  • Current trends in consumption of multimedia content using online streaming platforms: A user-centric survey
    • Przemysław Falkowski-Gilski
    • Tadeus Uhl
    2020 Computer Science Review

    In its early days, consumption of multimedia content was only possible at a stationary terminal device. The music player was located at home, and had to have a physical drive. Over the last decade, there has been an enormous increase in the number of online streaming platforms. These services enable users to consume rich multimedia content on various devices. Thanks to the widespread and availability of portable devices, any person connected to the Internet can access the same content, anytime and everywhere. This fact has forced wireless technologies to put significant emphasis on supporting high-quality content and on-demand services. However, energy consumption of handheld devices along with network bandwidth limitations are still the chief bottlenecks that today’s consumers face. This paper focuses on the consumption of multimedia content using mobile devices. It describes a user case study, carried out in 2019 on 150 individuals from three age groups, that is: 16–18, 19–24, and 25–35 years old, with 50 participants in each group. This survey covers the development of online streaming platforms and aims to help content providers, service providers and policy makers when designing and evaluating systems and services.

  • Curve Curvature Analysis of a Grain Trajectories in Variable Honing of Cylindrical Holes of Thin Wall Cylinder Liners as a Honing Process Optimization Strategy
    • Piotr Sender
    2020 Full text SpringerPlus

    The main problem of honing of thin wall cylinder liners is a thermal distortion of honed holes. The higher the value of the temperature of the honed workpiece, the greater its holes deformation. The paper presents a method of reducing the temperature occurring in the honing process as a result of the application of a variable honing kinematics conditions with particular emphasis on the analysis of the effect of the value of the sum of radii of curve curvature on honed workpieces temperature . The lower value of the sum of curve curvatures radius of abrasive grain trajectories function affects the honed workpiece temperature decrease for a longer path length. The curve curvature radius of the abrasive grain paths function in the variable kinematic condition of honing of cylindrical holes can be used to improve honing of thin wall cylinder liners due to decreasing of amount temperature received in honing process.

  • Cutting model parameters from frame sawing of natural and impregnated Scots pine (Pinus sylvestris L.)
    • Gerhard Sinn
    • Daniel Chuchała
    • Kazimierz Orłowski
    • Piotr Taube
    2020 Full text European Journal of Wood and Wood Products (HOLZ ALS ROH-UND WERKSTOFF)

    In this paper, absolute and density normalized cutting model parameters of natural and impregnated Scots pine (Pinus sylvestris L.) are shown and a method for the calculation of their corresponding material properties in the principal material directions of wood is presented. The parameters were determined from measurements of cutting power on a sash gang saw, and are in detail the fracture toughness and the shear yield strength of wood. The cutting model used for fitting the data and calculating the parameters is based on a minimum energy criterion originally developed to describe an orthogonal single tooth cutting process where the chip of an isotropic material is built by shear. The effects of impregnation on wood are clearly visible in cutting power and model parameters, where for large chips less power is required compared to natural wood. Impregnated pine wood shows a reduced value of shear yield strength compared to natural pine whilst the correlated fracture toughness increased. The observed behavior might be explained by a lower moisture content of the impregnated pine compared to natural wood. Orthotropic fracture toughness and shear yield strength constants of natural and impregnated Scots pine might be used to predict cutting power for other cutting geometries and processes like circular sawing.

  • Cycling as a Sustainable Transport Alternative in Polish Cittaslow Towns
    • Agnieszka Jaszczak
    • Agnieszka Morawiak
    • Joanna Żukowska
    2020 Full text Sustainability

    It is well known that growing motor traffic in urban areas causes air pollution and noise which affects the environment and public health. It is hardly surprising then that cycling should be used as an alternative mode of transport, not just in major cities but also in smaller ones including those that are members of the Cittaslow network. Their approach is based on sustainable development, care for the environment and transport solutions which will support a healthy lifestyle, reduced energy consumption and fewer emissions. The objective of the article is to analyse how well cycling is used as a means of transport in Polish Cittaslow towns. For this purpose, an analysis was conducted to understand how towns use their transport space to ensure accessibility and road safety. Reference is made to revitalisation programmes of Cittaslow towns with focus on what has been done to improve and build cycle paths in each town and outside of it. The work uses the following research methods: analysis of the literature, analysis of documents, including analysis of road incidents and traffic count. It has been demonstrated that cycling infrastructure in the towns under analysis has been marginalised. As a result, recommendations and suggestions are given which may inform decisions on how to build and transform cycling infrastructure in Cittaslow towns and in similar towns in Poland and abroad.

  • Cyclodextrin polymers as efficient adsorbents for removing toxic non-biodegradable pimavanserin from pharmaceutical wastewaters
    • Koleta Hemine
    • Anna Skwierawska
    • Agata Kernstein
    • Katarzyna Kozłowska-Tylingo
    2020 Full text CHEMOSPHERE

    Presence of even small amount of active pharmaceutical ingredients in the environment carries risks tohuman and animal health, presenting an important issue. The paper presents issues related to the newdrug - pimavanserin (PMV). Biological treatment efficiency of pimavanserin (PMV) was evaluated usinglab-scale Sequencing Batch Reactor (SBR). It has been shown to have a negative effect on aquatic or-ganisms by classifying it as a toxic compound (EC50¼8 mgL1). The level of biological degradation ofPMV was insufficient (37%) and intensively foam formation caused operational problems. For this reason,in this study polymers based on cyclodextrins (CDs) were synthesized and used as adsorbents alternativeto active carbons to effectively separate PMV from real industrial waste streams. Crosslinkedb- andg-CDpolymers (b- andg-NS), obtained in reaction with 1,10-carbonyldiimidazole (CDI), were fully character-ized by physicochemical methods. The adsorption equilibrium data were interpreted using Freundlichand Langmuir models. The sorption process was fast (60 s) and the efficiency of PMV separation frommodel waste waters was 93% and 81% forb- andg-NS, respectively. Maximum polymer capacity wasfound at 52.08 mg g1forb-NS and 23.26 mg g1forg-NS. The interactions of PMV with CDs have beenstudied and indicate that major mechanism of the sorption is based on supramolecular interaction andcapture to polymer network. Described biodegradable and reusable materials are perfect example ofcorrectly selected adsorbent for separation of target substance from postproduction aqueous media

  • Cząsteczki mikroRNA - nowy biologicznie aktywny składnik mleka kobiecego
    • Patrycja Jakubek
    • Joanna Cieślewicz
    • Agnieszka Bartoszek-Pączkowska
    2020 Full text Postępy Higieny i Medycyny Doświadczalnej

    Cząsteczki mikroRNA są krótkimi, niekodującymi oligonukleotydami odpowiadającymi za potranskrypcyjną regulację ekspresji genów. W wyniku ich aktywności kontrolowanych jest wiele procesów komórkowych oraz szlaków sygnalizacyjnych. Od 2010 roku wiadomo, że wchodzą one w skład mleka kobiecego, które obecnie uznaje się za jedno z najbogatszych pokarmowych źródeł mikroRNA. Funkcje tych cząsteczek w organizmie karmionego mlekiem matki dziecka są związane z kształtowaniem się układu odpornościowego, wzrostem i prawidłowym rozwojem. Wykazano, że cząsteczki mikroRNA pochodzące z mleka kobiecego są stabilne w warunkach in vitro symulujących trawienie w przewodzie pokarmowym niemowlęcia oraz mogą podlegać wchłanianiu przez enterocyty, przez co stanowią potencjalnie bioaktywny składnik mleka kobiecego sprzyjający rozwojowi niemowląt karmionych piersią. Ochronę przed degradacją w wyniku działania RNaz bądź niskiego pH zapewnia otoczka egzosomów, które stanowią nośnik mikroRNA we frakcji odtłuszczonej mleka, natomiast we frakcji lipidowej i komórkowej funkcję tę przypisuje się koloidalnym skupiskom pęcherzyków, zwanych kuleczkami tłuszczowymi, oraz laktocytom. W przeciwieństwie do mleka matki, sztuczne mieszanki mlekozastępcze zawierają tylko nieliczne cząsteczki mikroRNA – co więcej – wywodzące się od innych organizmów. Można przypuszczać, że dodatek krótkich RNA o sekwencjach identycznych z mikroRNA występującymi naturalnie w mleku kobiecym do preparatów do karmienia zastępczego niemowląt może stać się nowym, ważnym składnikiem mieszanek mlekozastępczych.

  • Czy komputer może zrobić błąd rachunkowy?
    • Joanna Raczek
    2020 Programista Junior

    W szkole błędy rachunkowe nie są mile widziane, w dodatku zazwyczaj nie wolno na lekcjach matematyki używać kalkulatorów. Jaka szkoda! Przecież kalkulator nigdy się nie myli! Ale czy na pewno?

  • Czy stan oznakowania dróg samorządowych ma wpływ na bezpieczeństwo ruchu drogowego?
    • Olga Białczak- Koprowska
    • Alicja Gardocka
    • Joanna Wachnicka
    2020 Drogownictwo

    Głównym celem artykułu była analiza stanu oznakowania dróg wojewódzkich oraz bezpieczeństwa ruchu drogowego na dwóch drogach wojewódzkich zlokalizowanych w województwie pomorskim, na których nastąpił wzrost wypadków w latach 2015-2017 w stosunku do lat 2012-2014. Badanie rozpoczęto od przeanalizowania stanu bezpieczeństwa ruchu drogowego bazując na danych o wypadkach. Następnie udano się na wizję lokalną, gdzie za pomocą oględzin sprawdzono stan oznakowania pionowego i poziomego. Podczas badania sprawdzono aktualny stan techniczny oznakowania, widoczność znaków, prawidłowość oznakowania oraz jego wpływ na bezpieczeństwo ruchu. Zwrócono także uwagę na stan techniczny jezdni oraz otoczenie wokół drogi. Zbadano odcinek biegnący od okolic miejscowości Babidół do okolic miejscowości Piekło Dolne na drodze wojewódzkiej 221 oraz odcinek biegnący od miejscowości Mierzeszyn do miejscowości Horniki Dolne na drodze 226. Głównym problemem na przeanalizowanych odcinkach drogi wojewódzkiej 221 i 226 była niedostateczna szerokość jezdni, która jest niedostosowana do natężenia ruchu panującego na analizowanym odcinku. Szerokość jezdni nie uwzględnia ruchu pieszych, całe pobocze przysłaniają korony drzew rosnące przy drodze, jednocześnie zasłaniają one także znaki pionowe. Oznakowanie pionowe i poziome przed zakrętami na drodze wojewódzkiej nr 226 w ogóle nie występuje, natomiast na drodze wojewódzkiej nr 221 i 227 oznakowanie poziome jest nieczytelne i wytarte, a oznakowanie pionowe jest zbyt późno. Na drodze wojewódzkiej nr 221 występują odcinki dróg na których mamy nagromadzenie znaków drogowych, natomiast na drodze wojewódzkiej nr 226 mamy sytuację skrajną pokazującą ewidentne braki w oznakowaniu szczególnie poziomym. Na zbadanych odcinkach dróg wojewódzkich przejścia są zaniedbane oraz niewidoczne z punktu widzenia kierowcy. Podczas badań odcinków wybranych dróg wojewódzkich zauważono, że oznakowanie pionowe jest nieczytelne, stare oraz zniszczone. 40% oznakowania pionowego nie posiada naklejek identyfikujących ze znakiem producenta, rokiem produkcji i typem folii odblaskowej. W złym stanie są również słupki hektometryczne, które w warunkach nocnych są niezbędne do wyznaczania geometrii drogi. Są one brudne, nieczytelne, porośnięte roślinnością oraz ścięte- prawdopodobnie po zdarzeniach drogowych. Znacznie gorzej jest z oznakowaniem poziomym, którego nie ma w ogóle lub jest ono niewidoczne.