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Gdańsk University of Technology

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  • Diagnostics and monitoring of the longest span extradosed bridge in Europe
    • Mikołaj Miśkiewicz
    • Krzysztof Wilde
    2019

    The article presents complex diagnostic procedures applied for the purpose of behavior analysis of the extradosed bridge with the longest span in Europe that was built in 2018 in Poland. The system of health monitoring was used to: register internal forces in temporary supports, monitor concrete bonding, perform in situ diagnostics and operation tests. The bridge is a continuous four-span structure with spans theoretical lengths equaling: 132.5+206.0+206.0+132.5 m. During the construction of the bridge, two technical monitoring systems were used. As a consequence of their application, it was possible to carry out works with the lowest level of risk and therefore the work schedule was accelerated. The first of systems was designed to measure forces transferred to temporary supports during cantilever construction stages. The second system was designed to measure changes of the strength of curing concrete, after it was poured at the site, which allowed to speed up the removal of the scaffoldings and post-tension of cross section with cables. When the bridge was finished, a Structural Health Monitoring (SHM) system was installed and final acceptance tests were launched. The obtained results were used to validate theoretical assumptions done at the stage of the bridge structural design and provided insight into the complex bridge behavior.

  • Diagnostics of pillars in St. Mary’s Church (Gdańsk, Poland) using the GPR method
    • Jacek Lachowicz
    • Magdalena Rucka
    2019 Full text International Journal of Architectural Heritage

    The main goal of this study was non-destructive evaluation of pillars in the St. Mary’s Church (Gdańsk, Poland) using the ground penetrating radar (GPR) technique. The GPR inspection was conducted on four brick masonry pillars and five pillars strengthened by reinforced concrete jacketing. Data were acquired with a 2 GHz antenna along longitudinal and transverse profiles. The study involved the estimation of the electromagnetic wave velocity in both brick and concrete, the inspection of the internal structure of the pillars and the precise identification of reinforcement bars. To determine the wave velocity in bricks, a novel mathematical model was developed. Finite-difference time-domain (FDTD) simulations were used to verify and assess the feasibility of the proposed model. Finally, GPR maps were processed using the hyperbolic summation method to visualize the reinforcement distribution in the concrete jacket.

  • Diagonalized Macromodels in Finite Element Method for Fast Electromagnetic Analysis of Waveguide Components
    • Krzysztof Nyka
    2019 Full text Electronics

    A new technique of local model-order reduction (MOR) in 3-D finite element method (FEM) for frequency-domain electromagnetic analysis of waveguide components is proposed in this paper. It resolves the problem of increasing solution time of the reduced-order system assembled from macromodels created in the subdomains, into which an analyzed structure is partitioned. This problem becomes particularly relevant for growing size and count of the macromodels, and when they are cloned in multiple locations of the structures or are used repeatedly in a tuning and optimization process. To significantly reduce the solution time, the diagonalized macromodels are created by means of the simultaneous diagonalization and subsequently assembled in the global system. For the resulting partially diagonal matrix, an efficient dedicated solver based on the Schur complement technique is proposed. The employed MOR method preserves frequency independence of the macromodels, which is essential for efficient diagonalization, as it can be performed once for the whole analysis bandwidth. The numerical validation of the proposed procedures with respect to accuracy and speed was carried out for varying size and count of macromodels. An exemplary finite periodical waveguide structure was chosen to investigate the influence of macromodel cloning on the resultant efficiency. The results show that the use of the diagonalized macromodels provided a significant solution speedup without any loss of accuracy

  • Diaminophosphinoboranes: effective reagents for phosphinoboration of CO2
    • Natalia Szynkiewicz
    • Anna Ordyszewska
    • Jarosław Chojnacki
    • Rafał Grubba
    2019 Full text RSC Advances

    The monomeric diaminophosphinoboranes readily react with CO2 under mild conditions to cleanly form products of the general formula R2P-C(=O)-O-B(NR2)2 in the absence of a catalyst. The isolated products from the CO2-phosphinoboration were fully characterized by NMR spectroscopy, IR spectroscopy, and X-ray diffraction. The mechanism of CO2 phosphinoboration with diaminophosphinoboranes was elucidated by DFT calculations.

  • Die Sandgrube „Köplitz“ – ein interessanter geologischer Aufschluss am Nordwestrand der Schmiedeberger Stauchendmoräne
    • Roland Wimmer
    • Ewa Wagner-Wysiecka
    2019 Full text Mauritiana

    Die Kiessandgrube Köplitz ermöglicht einen Einblick in die komplizierten, durch glazidynamische Überprägung gekennzeichneten geologischen Lagerungsverhältnisse im Bereich der Schmiedeberger Stauchendmoräne. Anhand neuer Geländedokumentationen wird ein kleiner Eindruck vom komplizierten injektiven „Fließfalten-Schuppenbau“ der Stauchendmoräne vermittelt. Die steil aufgerichteten, aus tertiären (Untermiozän bis Oligozän) und quartären (elster- bis saalekaltzeitlichen) Sedimenten bestehenden Schollenpakete streichen nahezu an der Geländeoberfläche aus. In den tertiären Ablagerungen wurden in den letzten Jahren wiederholt Einzelfunde von Bernstein gemacht. Sie wurden mittels der Infrarotspektroskopie untersucht.

  • Dietary antioxidants as a source of hydrogen peroxide
    • Michalina Grzesik
    • Grzegorz Bartosz
    • Ireneusz Stefaniuk
    • Monika Pichla
    • Jacek Namieśnik
    • Izabela Sadowska-Bartosz
    2019 FOOD CHEMISTRY

    Studies of 54 antioxidants revealed that 27 of them, mainly polyphenols, generated hydrogen peroxide (H2O2) when added to Dulbecco’s modified Eagle’s medium (DMEM), other media used for culture of mammalian and yeast cells and phosphate-buffered saline. The most active antioxidants were: propyl gallate (PG), (−)-epigallocatechin gallate (EGCG) and quercetin (Q). Chelex treatment and iron chelators decreased H2O2 generation suggesting that transition metal ions catalyze antioxidant autoxidation and H2O2 production. Green tea also generated H2O2; tea prepared on tap water generated significantly more H2O2 than tea prepared on deionized water. Ascorbic acid decreased H2O2 production although it generated H2O2 itself, in the absence of other additives. Lemon added to the tea significantly reduced generation of H2O2. Hydrogen peroxide generated in the medium contributed to the cytotoxicity of PG, EGCG and Q to human prostate carcinoma DU-145 cells, since catalase increased the survival of the cells subjected to these compounds in vitro.

  • Diethyl carbonate as a green extraction solvent for chlorophenol determination with dispersive liquid–liquid microextraction
    • Marek Tobiszewski
    • Weronika Zabrocka
    • Marta Bystrzanowska
    2019 Full text Analytical Methods

    The principles of green analytical chemistry indicate that the search for greener organic solvents for extraction applications is crucial. In this study diethyl carbonate (DEC) is proved to be a green solvent, as it is relatively nontoxic, obtainable from renewable resources and biodegradable. Here it is applied as an extraction solvent for chlorophenol determination in water samples with dispersive liquid–liquid microextraction. The multiobjective optimization for 7 chlorophenols is done with the design of an experiment combined with Derringer's desirability function. The optimized parameters in the extraction step are 300 mL of DEC, 0.5 mL of methanol, 8 mL of water sample and 7.5% of inorganic salt addition. The values of LOQ are from 0.01 to 0.3 mg L1, and CVs are between 7.1 and 17.3% for 7 CPs. In this study DEC is proved to be a promising, green solvent, applicable in analytical extractions.

  • Differences between selected volatile aromatic compound concentrations in sludge samples in various steps of wastewater treatment plant operations
    • Hubert Byliński
    • Justyna Aszyk
    • Paweł Kubica
    • Małgorzata Szopińska
    • Sylwia Fudala-Książek
    • Jacek Namieśnik
    2019 JOURNAL OF ENVIRONMENTAL MANAGEMENT

    Sewage sludge, one of the main wastes generated during wastewater treatment, constitutes an important source of emissions of volatile chemical compounds such as volatile aromatic compounds These substances may undergo various changes as a result of operations and unit processes, which affects their concentrations in sewage sludge. An important factor determining the potential hazardousness of volatile organic compounds is the quality of wastewater delivered to wastewater treatment plants and the technical and equipment solutions applied to wastewater. In this study, a rapid and sensitive headspace gas chromatography method, coupled with tandem mass spectrometry using the standard addition method, was developed for the determination of selected volatile aromatic compounds in sewage sludge samples collected at different stages from three wastewater treatment plants located in Poland. This study attempted to assess the relationship between differences in the emissions of representative VACs and the given stage of the technological process within three analysed wastewater treatment plants. The highest concentration levels were determined for p-cresol, with concentrations ranging from 44.0*101±5.6*101 ng/g of sludge (sludge from aerobic chamber, wastewater treatment plant no.2) to 47.7*102±6.9*102 ng/g of sludge (sludge from aerobic chamber, wastewater treatment plant no.1), while the lowest concentration levels were observed for chlorobenzene, with concentrations ranging from 0.1300 ± 0.0030 ng/g of sludge (sludge from anaerobic chamber, wastewater treatment plant no.2), to 0.2606 ± 0.0046 ng/g of sludge (primary sludge, wastewater treatment plant no.1). The repeatability of the method was better than 10%, with accuracy levels in the ranges 89%–108%.Wastewater treatment technologies and residual sludge management in the selected wastewater treatment plantsinfluenced volatile aromatic compounds emission. Furthermore, the diversity of the wastewater quality, depending on the catchment area, is also an important factor determining the differentiation in volatile aromatic compounds emission. The microbial composition of raw wastewater highly influenced not only the treatment effectiveness of wastewater treatment plants but also the production of intermediate products, such as volatile aromatic compounds, which may contribute to odour emissions.

  • Digital Government as Implementation Means for Sustainable Development Goals
    • Ignacio Marcovecchio
    • Mamello Thinyane
    • Elsa Estevez
    • Tomasz Janowski
    2019 Full text International Journal of Public Administration in the Digital Age

    One of the challenges for implementing Sustainable Development Goals (SDGs) is the measurement of indicators that represent progress towards such goals. Measuring such progress enables data-driven decision-making and management of SDG-relevant projects and strategies. The premise of this research is that measuring such indicators depends on measuring so-called means of implementation, i.e. activities that directly contribute to the achievement of SDGs. Building on this premise, this article studies how the measurement of digital government (DG) can contribute to the measurement of SDGs. In particular, how the indicators originating in three DG measurement instruments can inform the SDG indicators. The main finding is an alignment matrix, showing how the DG indicators contribute with varying level of specificity to the measurement of 10 SDG indicators.

  • Dimethyl ether (DME) as potential environmental friendly fuel
    • Patrycja Makoś
    • Edyta Słupek
    • Joanna Sobczak
    • Dawid Zabrocki
    • Jan Hupka
    • Andrzej Rogala
    2019 Full text E3S Web of Conferences

    In recent years, there has been a growing interest in replacing petroleum fuels with so-called second generation environmental friendly fuels. Compared to traditional petroleum fuels dimethyl ether (DME) could be used as a clean high-efficiency compression ignition fuel with reduced particulate matter (PM), sulfur oxides (SOx), hydrocarbons (HC), carbon monoxide (CO) as well as combustion noise. Compared to some of the other leading alternative fuel candidates i.e., methane, methanol, ethanol, compressed natural gas, DME appears to have the largest potential impact on society including well-to-wheel greenhouse gas emissions, non-petroleum feedstocks, well-to-wheel efficiencies, fuel versatility, infrastructure, availability, economics, and safety and should be considered as the fuel of choice for eliminating the dependency on petroleum. This paper reviews the properties and the DME combustion effects on environmental and they were compared to diesel characteristic as well as the effect of blending DME with liquefied petroleum gas (LPG), conventional diesel fuel and biodiesel were discussed.

  • Diphosphination of CO2 and CS2 mediated by frustrated Lewis pairs - catalytic route to phosphanyl derivatives of formic and dithioformic acid
    • Natalia Szynkiewicz
    • Łukasz Ponikiewski
    • Rafał Grubba
    2019 Full text CHEMICAL COMMUNICATIONS

    The first example of CO2 diphosphination is described. Reactions of unsymmetrical diphosphanes with CE2 (E = O, S) catalyzed by BPh3 insert a CE2 molecule into the P-P bond with formation of the products of the general formula R2P-E-C(=E)-PR2. The obtained CO2 adducts arise from synergistic interaction of diphosphane and borane with CO2 molecule.

  • Dirac fermions and possible weak antilocalization in LaCuSb2
    • Juan Chamorro
    • A. Topp
    • Y. Fang
    • Michał Winiarski
    • C. R. Ast
    • M. Krivenkov
    • A. Varykhalov
    • B. J. Ramshaw
    • Leslie Schoop
    • Tyrel McQueen
    2019 Full text APL Materials

    Layered heavy-metal square-lattice compounds have recently emerged as potential Dirac fermion materials due to bonding within those sublattices. We report quantum transport and spectroscopic data on the layered Sb square-lattice material LaCuSb2. Linearly dispersing band crossings, necessary to generate Dirac fermions, are experimentally observed in the electronic band structure observed using angle-resolved photoemission spectroscopy, along with a quasi-two-dimensional Fermi surface. Weak antilocalization that arises from two-dimensional transport is observed in the magnetoresistance, as well as regions of linear dependence, both of which are indicative of topologically nontrivial effects. Measurements of the Shubnikov–de Haas quantum oscillations show low effective mass electrons on the order of 0.065me, further confirming the presence of Dirac fermions in this material.

  • Discovering Rule-Based Learning Systems for the Purpose of Music Analysis
    • Grazina Korvel
    • Bożena Kostek
    2019 Full text Journal of the Acoustical Society of America

    Music analysis and processing aims at understanding information retrieved from music (Music Information Retrieval). For the purpose of music data mining, machine learning (ML) methods or statistical approach are employed. Their primary task is recognition of musical instrument sounds, music genre or emotion contained in music, identification of audio, assessment of audio content, etc. In terms of computational approach, music databases contain imprecise, vague and indiscernible data objects. Moreover, most of the machine learning algorithms outcomes are given as a black-box result. Also, underfitting or overfitting may occur, meaning that either the model description is not complex enough or the test set is too small or not sufficiently representative. Thus the goal is to generalize the model. To overcome some of these problems, rule-based systems may be used, e.g., based on rough set theory that shows the outcome in the form of rules interconnecting features retrieved from music. Thus, first, principles of rule-based classifiers and particularly rough sets (RS) are presented, showing their usability in the music domain. A potential of the rough set-based approach was shown in the context of music genre recognition. The results were analyzed in terms of the recognition rate and computation time efficiency.

  • Discovery of Stylistic Patterns in Business Process Textual Descriptions: IT Ticket Case
    • Nina Rizun
    • Aleksandra Revina
    • Vera Maister
    2019 Full text

    Growing IT complexity and related problems, which are reflected in IT tickets,create a need for new qualitative approaches. The goal isto automate the extraction of main topics described in tickets in order to provide high quality support for the IT process workers and enablea smooth service delivery to the end user. Present paper proposes a method of knowledge extraction in a form of stylistic patterns in business process (BP) texts, here in incoming IT tickets texts. Hereby, the authors set an objective to predicttheir readability andperceivedcomplexityfor a process worker, what will influencefurther tasks execution. The results of experimental analysis of a data set of incoming ticket texts from anITIL-based Change Management process showed that the specificity of stylistic patterns expressing the readability of a ticket and perceived complexity could be identified with the help of proposed measures of the ticket length, parts-of-speech distributions and wording style (PDF) Discovery of Stylistic Patterns in Business Process Textual Descriptions: IT Ticket Case. Available from: https://www.researchgate.net/publication/331843977_Discovery_of_Stylistic_Patterns_in_Business_Process_Textual_Descriptions_IT_Ticket_Case [accessed Jun 23 2019].

  • Discussion on “Coupled effective stress analysis of insertion problems in geotechnics with the Particle Finite Element Method” by L. Monforte, M. Arroyo, J.M. Carbonell, and A. Gens
    • Jakub Konkol
    • Lech Bałachowski
    2019 Full text COMPUTERS AND GEOTECHNICS

    Addressed here is the Particle Finite Element Method (PFEM) modelling of undrained CPTu penetration with regard to a reference analytical solution based on the Spherical Cavity Expansion Method (SCEM). Also discussed is the choice of the soil model and its parameters. The effect of cone interface friction on CPTu simulation is analyzed in a series of penetration tests using Arbitrary Lagrangian-Eulerian (ALE) and Updated Lagrangian (UL) methods. The results of the simulations are compared with the Authors’ proposal.

  • Dispersive liquid-liquid microextraction combined with gas chromatography–mass spectrometry for in situ determination of biogenic amines in meat: Estimation of meat's freshness
    • Wojciech Wojnowski
    • Justyna Płotka-Wasylka
    • Jacek Namieśnik
    2019 Full text MICROCHEMICAL JOURNAL

    A dispersive liquid-liquid microextraction (DLLME) gas chromatography–mass spectrometry (GC–MS) technique was developed for the determination of selected biogenic amines (BAs) in samples of poultry, pork and beef. Prior to the extraction process, an appropriate volume of sodium hydroxide solution was added to each of the portioned samples. Next, samples were homogenized, centrifuged and finally sonicated at an increased temperature. After another centrifugation, the supernatant was made up to 50 mL in a calibrated flask. Subsequently, 5 mL of supernatant was separately subjected to a derivatization and extraction procedure. A mixture of methanol (dispersive solvent; 210 μL), chloroform (extractive solvent; 300 μL), and isobutyl chloroformate (derivatizing reagent; 100 μL) was used in the extraction process together with an admixture of pyridine and HCl in order to eliminate the by-products. The application of the method enables fast derivatization and extraction of the BAs and a straightforward and rapid sample enrichment. It displayed good linearity, intra- and inter-day precision and good recoveries. The proposed methodology is characterized by low limits of detection and quantification (0.003–0.009 μg/g and 0.009–0.029 μg/g, respectively). The green character of the method was established based on the results of two tools, namely the Analytical Eco-Scale and GAPI. It was successfully used to analyse samples of poultry, porcine and bovine meat. Multivariate statistical data analysis was applied in order to evaluate the potential use of the determined BAs as spoilage markers of particular meat types.

  • Dissociative ionization dynamics of dielectric gas C3F7CN
    • Milos Ranković
    • J Chalabala
    • Mateusz Zawadzki
    • Jaroslav Kočišek
    • Petr Slavíček
    • Juraj Fedor
    2019 PHYSICAL CHEMISTRY CHEMICAL PHYSICS

    Fluoronitrile C3F7CN is a promising candidate for the replacement of SF6 dielectric gas in high-voltage insulation. We present a combined experimental and theoretical study on its ionization dynamics probed in the 0-100 eV energy range. We exploited the total ion collection technique to determine the absolute ionization cross section, mass spectrometry to determine the fragment branching ratios and ab initio nonadiabatic molecular dynamics to simulate the ionization process. The latter two approaches showed the dominating presence of the CF+3 cation over the whole electron energy range. The Binary-Encounter-Bethe (BEB) approximation reproduces experimental cross sections very well and reveals that the ionization from a surprisingly large number of orbitals contributes almost equally to the processes. We show that the initially populated cation excited states undergo an ultrafast internal conversion to the ground state where the dissociation into a single decay channel takes place. Implications for the use of C3F7CN as an insulating material are discussed.

  • Distortional buckling of composite thin-walled columns of a box-type cross section with diaphragms
    • Czesław Szymczak
    • Marcin Kujawa
    2019 Full text ACTA MECHANICA

    Distortional buckling of axially compressed columns of box-like composite cross sections with andwithout internal diaphragms is investigated in the framework of one-dimensional theory. The channel membersare composed of unidirectional fibre-reinforced laminate. Two approaches to the member orthotropic materialare applied: homogenization based on the theory of mixture and periodicity cells, and homogenization basedon the Voigt–Reuss hypothesis. The principle of stationary total potential energy is applied to derive thegoverning differential equation. The obtained buckling stress is valid in the linear elastic range of columnmaterial behaviour. Numerical examples address simply supported columns, and analytical critical stressformulas are derived. The analytical and FEM solutions are compared, and sufficient accuracy of the resultsis observed.

  • Distributed Architectures for Intensive Urban Computing: A Case Study on Smart Lighting for Sustainable Cities
    • Higinio Mora
    • Jesus Peral
    • Antonio Ferrandez
    • David Gil
    • Julian Szymański
    2019 Full text IEEE Access

    New information and communication technologies have contributed to the development of the smart city concept. On a physical level, this paradigm is characterised by deploying a substantial number of different devices that can sense their surroundings and generate a large amount of data. The most typical case is image and video acquisition sensors. Recently, these types of sensors are found in abundance in urban spaces and are responsible for producing a large volume of multimedia data. The advanced computer vision methods for this type of multimedia information means that many aspects can be dynamically monitored, which can help implement value-added applications in the city. However, obtaining more elaborate semantic information from these data poses significant challenges related to a large amount of data generated and the processing capabilities required. This work aims to address these issues by using a combination of cloud computing technologies and mobile computing techniques to design a three-layer distributed architecture for intensive urban computing. The approach consists of distributing the processing tasks among a city’s multimedia acquisition devices, a middle computing layer, known as a cloudlet, and a cloud-computing infrastructure. As a result, each part of the architecture can now focus on a small number of tasks for which they are especially designed, and data transmission communication needs are significantly reduced. To this end, the cloud server can hold and centralise the multimedia analysis of processed results from the lower layers. Finally, a case study on smart lighting is described to illustrate the benefits of using the proposed model in smart city environments.

  • DISTRIBUTION OF FLOWS IN A CHANNEL NETWORK UNDER STEADY FLOW CONDITIONS
    • Dariusz Gąsiorowski
    • Wojciech Artichowicz
    2019 Full text Acta Scientiarum Polonorum Formatio Circumiectus

    The article presents an algorithm for calculating the distribution of flow in a junction of open channel network under steady flow conditions. The article presents a simplified calculation algorithm used to estimate the distribution of flow in a network of channels under steady flow conditions. The presented algorithm is based on the continuity equation and a simplified energy equation. To describe the relationship between the depth of water and the flow rate, the Manning’s equation was used to express discharge in the main channel, whereas in case of other channels, with hydraulic structures, appropriate equations describing the flow over a weir and through the culverts were used. Substitution of the abovementioned relationships with the continuity equation leads to a non-linear algebraic equation with respect to the water level. The resulting equation can be solved with iterative numerical methods. Calculation example using the proposed algorithm was carried out for the hydraulic system located on the Strzyża stream in Gdańsk. The presented approach can be an alternative to analytical-graphic method and it does not require formulation of the boundary problem for the

  • Distribution Transformer with Multi-Zone Voltage Regulation for Smart Grid System Application
    • Ryszard Strzelecki
    • Wojciech Matelski
    • Robert Małkowski
    • Valentin Tomasov
    • Leszek Wolski
    • Antoni Krahel
    2019 Full text

    The article presents four concepts of the multi-zone voltage regulation (MZVR) system. It is a combination of a distribution transformer with an on-load tap-changer, for step voltage regulation, and a power electronic converter, dimensioned for a fraction of MZVR power, realizing continuous voltage regulation, supplemented by a special switch, the so-called bypass. This allows voltage regulation at high resolution, wide range and with high dynamics and increased reliability. The work contains selected computer simulation results of the continuous regulation system, and considerations about extending the MZVR continuous voltage regulation range and its power level.

  • DME as alternative fuel for compression ignition engines – a review
    • Denys Stepanenko
    • Zbigniew Kneba
    2019 Full text Combustion Engines

    The ecological issues and the depletion of crude oil, has led the researchers to seeking for non-petroleum based alternative fuels, along with more advanced combustion technologies, and after-treatment systems. The use of clean alternative fuels is the one of the most perspective method that aiming at resolving of the said issues. One of the promising alternative fuels that can be used as a clean highefficiency compression ignition fuel with reduced of toxic emissions is dimethyl ether (DME). Moreover, it can be produced from various feedstocks such as natural gas, coal, biomass and others. This article describes the properties and the potential of DME application on the combustion and emission reduction characteristics of the compression ignition engines.

  • DMSO hydration redefined: Unraveling the hydrophobic hydration of solutes with a mixed hydrophilic–hydrophobic characteristic
    • Aneta Panuszko
    • Piotr Bruździak
    • Maciej Śmiechowski
    • Marcin Stasiulewicz
    • Joanna Stefaniak
    • Janusz Stangret
    2019 Full text JOURNAL OF MOLECULAR LIQUIDS

    Hydrophobic hydration of solutes with a mixed hydrophilic--hydrophobic characteristics is still poorly understood. This is because both experimental and theoretical methods find it difficult to see the ice-like water structure around the nonpolar solute groups, unlike hydrogen bonds with the hydrophilic groups. In order to unravel this problem, we have investigated DMSO hydration by means of infrared spectroscopy and theoretical methods, namely DFT, ONIOM calculations and AIMD simulations, which allowed us to redefine its hydration. In dilute DMSO solutions the clathrate-like water is formed around the DMSO molecule, supported by interactions of water molecules with the methyl hydrogens (the blue-shifted hydrogen bonds). The cage is constructed by water molecules that form hydrogen bonds of the comparable energy and length with the SO group and between water molecules. When the construction of the cage is completed, DMSO molecule partially regains its rotational freedom inside. Strong hydrogen bonds within the frame are masked by the relatively small population of weakened hydrogen bonds of water molecules in the vicinity of the SO group, due to the improper fit to the bulk water of water molecules hydrogen bonded to the oxygen atom of DMSO. We also propose a new explanation of the highly non-ideal mixing behavior of aqueous DMSO solutions at the eutectic point, as the positive excess entropy of the equimolar amounts of molecular complexes distinguished in the system.

  • DNA Methylation Changes Induced by Redox-Active Compounds—Choosing the Right PCR-Based Method
    • Patrycja Jakubek
    • Jovana Rajić
    • Monika Baranowska
    • Melita Vidaković
    • Agnieszka Bartoszek-Pączkowska
    • Jacek Namieśnik
    2019 Full text Proceedings

    The impact of catechins on the expression profile of redox-related genes in HT29 cell line has been studied recently by our group using Oxidative Stress RT2 Profiler PCR Array. Within the examined panel of 84 genes, the down-regulation of SRXN1 gene was unique among other up-regulated genes. We hypothesized that the observed down-regulation resulted from DNA methylation and have exploited this observation to choose the proper strategy to monitor the changes in DNA methylation patterns incurred by dietary antioxidants. The current study verified two PCR-based approaches.

  • Do online reviews reveal mobile application usability and user experience? The case of WhatsApp
    • Anna Baj-Rogowska
    • Paweł Weichbroth
    2019 Full text Annals of Computer Science and Information Systems

    The variety of hardware devices and the diversity of their users imposes new requirements and expectations on designers and developers of mobile applications (apps). While the Internet has enabled new forms of communication platform, online stores provide the ability to review apps. These informal online app reviews have become a viral form of electronic wordof-mouth (eWOM), covering a plethora of issues. In our study, we set ourselves the goal of investigating whether online reviews reveal usability and user experience (UUX) issues, being important quality-in-use characteristics. To address this problem, we used sentiment analysis techniques, with the aim of extracting relevant keywords from eWOM WhatsApp data. Based on the extracted keywords, we next identified the original users’ reviews, and individually assigned each attribute and dimension to them. Eventually, the reported issues were thematically synthesized into 7 attributes and 8 dimensions. If one asks whether online reviews reveal genuine UUX issues, in this case, the answer is definitely affirmative.

  • Doktorant PG – Jutronauta w NASA
    • Adam Dąbrowski
    2019 Full text Pismo PG

    Mgr inż. Adam Dąbrowski, doktorant i asystent na Wydziale Mechanicznym, został laureatem konkursu Gazety Wyborczej „Jutronauci. Bilet za horyzont”, w ramach którego odbył staż w Jet Propulsion Laboratory (JPL), laboratorium NASA w Pasadenie w Kalifornii.

  • Dokumentacja oraz wnioski z badań prototypowego stropu typu filigran z wkładką styropianową dla firmy Strobud Prefabrykacja sp. z o.o.
    • Krystyna Nagrodzka-Godycka
    • Marek Wesołowski
    • Jarosław Kondrat
    • Maciej Solarczyk
    2019

    Niniejsze opracowanie stanowi dokumentację oraz wnioski z badań prototypowego stropu typu filigran z wkładką styropianową.

  • Domination subdivision and domination multisubdivision numbers of graphs
    • Magda Dettlaff
    • Joanna Raczek
    • Jerzy Topp
    2019 Full text Discussiones Mathematicae Graph Theory

    The domination subdivision number sd(G) of a graph G is the minimum number of edges that must be subdivided (where an edge can be subdivided at most once) in order to increase the domination number of G. It has been shown [10] that sd(T)<=3 for any tree T. We prove that the decision problem of the domination subdivision number is NP-complete even for bipartite graphs. For this reason we define the domination multisubdivision number of a nonempty graph G as a minimum positive integer k such that there exists an edge which must be subdivided k times to increase the domination number of G. We show that msd(G)<=3 for any graph G. The domination subdivision number and the domination multisubdivision number of a graph are incomparable in general, but we show that for trees these two parameters are equal. We also determine the domination multisubdivision number for some classes of graphs.

  • Doped Nanocrystalline Diamond Films as Reflective Layers for Fiber-Optic Sensors of Refractive Index of Liquids
    • Monika Kosowska
    • Daria Majchrowicz
    • Kamatchi J Sankaran
    • Mateusz Ficek
    • Ken Haenen
    • Małgorzata Szczerska
    2019 Full text Materials

    This paper reports the application of doped nanocrystalline diamond (NCD) films—nitrogen-doped NCD and boron-doped NCD—as reflective surfaces in an interferometric sensor of refractive index dedicated to the measurements of liquids. The sensor is constructed as a Fabry–Pérot interferometer, working in the reflective mode. The diamond films were deposited on silicon substrates by a microwave plasma enhanced chemical vapor deposition system. The measurements of refractive indices of liquids were carried out in the range of 1.3 to 1.6. The results of initial investigations show that doped NCD films can be successfully used in fiber-optic sensors of refractive index providing linear work characteristics. Their application can prolong the lifespan of the measurement head and open the way to measure biomedical samples and aggressive chemicals.

  • Doraźna nośność słupów o przekroju kołowym z rur FRP wypełnionych betonem Badania, teoria, obliczanie
    • Marcin Abramski
    2019

    Praca ma charakter monografii opisującej aktualny stan wiedzy z zakresu badań, teorii i projektowania słupów CFFT (concrete-filled fiber-reinforced polymer tube). Celem prowadzonych przez autora prac studialnych i badań własnych, w tym eksperymentalnych, jest szczegółowa analiza doraźnej nośności i zachowania się słupów CFFT poddanych ściskaniu osiowemu i mimośrodowemu. W pierwszym rozdziale wyjaśniono motywację autora do podjęcia tej tematyki, przedstawiając ją jednocześnie jako niszę badawczą. W rozdziale drugim opisano na konkretnych przykładach najbardziej odpowiednie dla słupów CFFT obszary zastosowań: jako obiekty infrastruktury morskiej i mostowej. Rozdziały trzeci i czwarty mają na celu przedstawienie aktualnego stanu wiedzy, odpowiednio na temat zachowania betonu skrępowanego w słupach z rur stalowych lub kompozytowych wypełnianych betonem (concrete filled tube) oraz uwzględniania efektów drugiego rzędu w obliczaniu nośności słupów z betonu. W rozdziale trzecim przywołano wyselekcjonowane, zdaniem autora – mające charakter najbardziej poznawczy badania obce i opatrzono je komentarzem. W rozdziale czwartym natomiast wzięto pod uwagę normatywy projektowania słupów z betonu: przede wszystkim europejskie (Eurokody), ale także amerykańskie, międzynarodowe i wybrane krajowe. W rozdziale piątym, najbardziej obszernym, przedstawiono badania eksperymentalne, w przeważającej części własne, poświęcone nośności i zachowaniu słupów CFFT ściskanych osiowo lub mimośrodowo. W całości własne w tym rozdziale są obszerne badania eksperymentalne własności kompozytów FRP rur, których użyto do wykonania wspomnianych słupów. Dla trzech zastosowanych kompozytów wyznaczono podstawowe stałe materiałowe, wymagane w teorii liniowej sprężystości. Ponieważ były to badania nietypowe dla inżynierii budowlanej, zastosowano procedury nie tylko normowe, lecz także własne, zaproponowane przez autora. Wszystkie przeprowadzone badania opisane w pracy pozwoliły na sformułowanie propozycji metody wyznaczania doraźnej nośności słupów CFFT. Przedstawiono ją w rozdziale szóstym. Opracowując metodę, wzorowano się przede wszystkim na Eurokodach oraz na amerykańskim normatywie poświęconym projektowaniu słupów CFFT. Dla zaproponowanej metody opracowano program komputerowy i przy jego użyciu sprawdzono zgodność wyników nośności obliczonych metodą autorską z wynikami eksperymentów. Na zakończenie nakreślono kierunki dalszych badań nad słupami CFFT.

  • Drewniane więźby dachowe żuławskich domów podcieniowych typu III – badania, stan zachowania, analiza
    • Tomasz Zybała
    2019 Full text Budownictwo i Architektura

    Zabytkowe domy podcieniowe ujścia Delty Wisły były obiektem zainteresowań wielu badaczy, jednak ich prace koncentrowały się głównie na aspektach historyczno-architektonicznych. Nie ma publikacji skupiających się na szczegółach i dokładnych analizach ustrojów budowlanych dla tej grupy historycznych obiektów. Artykuł jest rezultatem badań terenowych, kwerendy archiwalnej i obliczeń wykonanych przez autora. W pracyprzeanalizowano konstrukcje więźb dachowych zachowanych domów podcieniowych typu III.Autor wykonał zestawienia elementów nośnych dachów, połączeń ciesielskich, kątów nachylenia krokwi, opisał także stan zachowania wiązarów dachowych.Praca zawiera również obliczenia średniej objętości materiału konstrukcyjnego wiązara więźby dachowej przypadającego na metr kwadratowy rzutu połaci dachowej.

  • DREWNO i DOM. Drewno w architekturze mieszkalnej dawnego Wejherowa
    • Anita Jaśkiewicz-Sojak
    • Kurpiewski Maciej
    2019

    Drewno jest jednym z podstawowych materiałów budowlanych, który bardzo często był wykorzystywany w budownictwie minionych okresów historycznych. Drewno stosowano zarówno jako materiał konstrukcji budynków lub ich części, jak i tworzywo do kształtowania poszczególnych elementów i detalu architektonicznego. Wystawa przedstawia różne sposoby wykorzystania tego materiału budowlanego w architekturze mieszkaniowej Wejherowa w przeszłości. Rozważania na ten temat zostały zilustrowane archiwalnymi fotografiami i kartami pocztowymi dawnego Wejherowa, powstałymi w końcu XIX i w pierwszej połowie XX wieku. Ilustracjom towarzyszą także eksponaty, drewniane elementy zabytkowych budynków, które udało się zabezpieczyć i zachować. Są one dowodami na kruchość i nietrwałość drewna oraz świadczą o tym, że materialne dziedzictwo drewniane powoli znika z miejskiego krajobrazu i - paradoksalnie - powoli przekształca się w dziedzictwo niematerialne.

  • Droga S7 Koszwały – Kazimierzowo – geotechniczne aspekty inwestycji.
    • Grzegorz Horodecki
    2019 Magazyn Autostrady

    W artykule przedstawiono ogólne informacje dotyczące geotechnicznych aspektów projektu i realizacji drogi S7 na odcinku Koszwały – Kazimierzowo, ze szczególnym uwzględnieniem rozwiązań z zastosowaniem technologii zamkniętego materaca odciążającego z kruszywa lekkiego – keramzytu geotechnicznego. Przedstawiono metody wzmocnienia podłoża przyjęte na etapie projektu oraz realizacji wraz z monitoringiem geotechnicznym.

  • Drop-coating deposition surface-enhanced Raman spectroscopy on silver substrates for biofluid analysis
    • Maciej Wróbel
    • Zufang Huang
    • Soumik Siddhanta
    • Ishan Barman
    2019 Full text

    Utilization of surface-enhanced Raman spectroscopy as a measurement technique is of particular interest in biodetection due to its superb chemical specificity and high sensitivity. The use of SERS substrates further improve this method by massive enhancement of the molecule Raman spectrum, permitting very low levels of detection. Therefore it is important to seek for new ways to develop reliable substrates, which are quickly and easily manufactured at a low cost. This paper describes the development of a simple and cost-effective substrate for the SERS detection. The substrate is synthesized from a silver ink on the glass, and its utilization for biodetection is shown. The hydrophobicity of the substrate permits the pre-concentration benefit of the drop-coating deposition, by the formation of the coffee-ring. This allows to achieve lower limits of detection, by effectively measuring areas with higher concentration of measured molecules than the initial sample. However, the different properties of the medium, such as the influence of protein types and amounts, may influence the ring formation mechanics, thus effectively changing the pre-concentration of the target analyte.

  • Dual-band antenna with improved gain for WLAN and ISM applications
    • Adrian Bekasiewicz
    • Sławomir Kozieł
    2019 ELECTRONICS LETTERS

    In this Letter, a dual-band antenna with an improved gain is proposed. The structure features 9.7 and 10.4 dBi gain within 2.4 GHz to 2.5 GHz and 5 GHz to 6 GHz bands, respectively. This makes it suitable for WLAN and ISM applications. The structure comprises an asymmetrical pair of radiators and slots suspended over a reflector. The antenna is optimised in a two-stage process using a trust-region-based gradient search algorithm. The design is compared to the state-of-the-art radiators reported in the literature. The numerical results are validated through measurements of the fabricated antenna prototype.

  • DWUKIERUNKOWY PRZEWODOWY SYSTEM TRANSMISJI MOWY PRZY WYKORZYSTANIU TECHNOLOGII BPL
    • Przemysław Jedlikowski
    • Grzegorz Debita
    • Przemysław Falkowski-Gilski
    • Marcin Habrych
    • Bogdan Miedziński
    • Jan Wandzio
    2019 Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

    Monitorowanie pracowników w środowisku podziemnym jest niezwykle ważnym zadaniem. Z uwagi na możliwe zagrożenia, konieczne jest opracowanie niezawodnego systemu komunikacji głosowej pomiędzy personelem a przełożonym. Dzięki wysokiej odporności na uszkodzenia mechaniczne, kable zasilające pracujące w technice BPL (Broadband over Power Line) wydają się doskonałym rozwiązaniem. W pracy przedstawiono w pełni funkcjonalny dwukierunkowy system transmisji mowy. Testy przeprowadzono w warunkach rzeczywistych, obejmujących szyb wydobywczy.

  • Dynamic Bankruptcy Prediction Models for European Enterprises
    • Tomasz Korol
    2019 Full text Journal of Risk and Financial Management

    This manuscript is devoted to the issue of forecasting corporate bankruptcy. Determining a firm’s bankruptcy risk is one of the most interesting topics for investors and decision-makers. The aim of the paper is to develop and to evaluate dynamic bankruptcy prediction models for European enterprises. To conduct this objective, four forecasting models are developed with the use of four different methods—fuzzy sets, recurrent and multilayer artificial neural network, and decision trees. Such a research approach will answer the question of whether changes in indicators are relevant predictors of a company’s coming financial crisis because declines or increases in values do not immediately indicate that the company’s economic situation is deteriorating. The research relies on two samples of firms—the learning sample of 50 bankrupt and 50 non-bankrupt enterprises and the testing sample of 250 bankrupt and 250 non-bankrupt firms.

  • Dynamic modeling of non-cylindrical curved viscoelastic single-walled carbon nanotubes based on the second gradient theory
    • Mohammad Malikan
    • Van Bac Nguyen
    • Rossana Dimitri
    • Francesco Tornabene
    2019 Full text Materials Research Express

    This paper is devoted to the theoretical study of the dynamic response of non-cylindrical curved viscoelastic single-walled carbon nanotubes (SWCNTs). The curved nanotubes are largely used in many engineering applications, but it is challenging in understanding mechanically the dynamic response of these curved SWCNTs when considering the influences of the material viscosity. The viscoelastic damping effect on the dynamic response is considered here by using the Kelvin-Voigt viscoelastic model. A modified shear deformation beam theory is here employed to formulate the governing partial differential equations. When the SWCNTs are considered in a small scale model, quantum impacts are important for a correct evaluation of the mechanical response of the nanosystem. This is here investigated by embedding the well-known nonlocal strain gradient approach into the governing equations. The extracted equations are solved by utilizing the Galerkin analytical approach in which the governing partial differential equations are reduced to ordinary differential equations and numerical findings are achieved for various boundary conditions. In order to evaluate the efficiency of the proposed theory, the outcomes in terms of natural frequencies of the vibrating nanotubes are verified with respect to the available literature. It follows a vast systematic study, where several parameters are varied to investigate the influences of geometrical properties involving different polygons of the SWCNTs on the dynamic response.

  • Dynamic tests of composite footbridge segment – experimental and numerical studies
    • Tomasz Wiczenbach
    • Tomasz Ferenc
    • Łukasz Pyrzowski
    • Jacek Chróścielewski
    2019 Full text MATEC Web of Conferences

    Experimental dynamic tests and numerical simulations of a 3 meters long segment of a footbridge made of polymer composites are presented in the paper. The span-length is reduced, however dimensions of cross-section are the same as the target footbridge. The segment structure is made of sandwich panels, which consist of fibre reinforced polymer (GFRP) laminates (skins) and a PET foam (core). The first part of the paper contains description and results of experimental dynamic tests, which were subjected to the structure. The excitations during these tests was realised by a group of people standing or jumping on the structure deck. The obtained results allowed to determine natural frequencies as well as damping ratios. Moreover, cyclic loading was applied to the structure deck to check the possibility of delamination or debonding occurrence, as a result of repetitive dynamic excitations. The second part contains validation of numerical model - results of numerical analysis and its comparison with the experimental ones.

  • Dynamics of the small-span railway bridge under moving loads
    • Marek Szafrański
    2019 Full text MATEC Web of Conferences

    The paper presents the results of dynamic analysis of the small-span railway bridge, subjected to an action of moving trains. Numerical simulations were performed using three different load models: series of moving forces, series of moving single-mass and double-mass oscillators. The parameters of the vehicle were taken from the existing EN57 train. The parameters of the bridge were taken from the existing steel span of 10,24 m long. In both cases, the dynamic parameters were identified based on free-response measurements using modal identification techniques. Vibrations of the midpoint of the bridge as well as the mass of the oscillator have been analyzed. Numerical results obtained for individual load models were compared with the results of in-situ tests performed under operating conditions.

  • Dynamiczna technika analizy fazy nadpowierzchniowej
    • Mariusz Marć
    • Krzysztof Formela
    2019 Tworzywa Sztuczne w Przemyśle

    Dążność do uzyskiwania miarodajnej informacji analitycznej na temat rodzaju oraz ilości związków chemicznych emitowanych z powierzchni materiałów polimerowych stanowi istotny czynnik w procesie rozwoju technik analitycznych, jako nieodzowny element kontroli jakości opracowywanych materiałów użytkowych. W pracy naświetlono najważniejsze informacje na temat rozwiązań konstrukcyjnych i aparaturowych zaliczanych do dynamicznych technik analizy fazy nadpowierzchniowej stosowanych do określania wielkości emisji związków chemicznych z grupy lotnych związków organicznych uwalnianych z materiałów wykonanych z tworzyw sztucznych oraz gumy. Wyznaczenie profilu emisji oraz najbardziej charakterystycznych związków chemicznych uwalnianych z powierzchni opracowanych materiałów może stanowić cenną informację na temat danego produktu jako jeden z elementów kontroli jakości.

  • Earthquake-Induced Pounding of Medium-to-High-Rise Base-Isolated Buildings
    • Hosein Naderpour
    • Payam Danaeifard
    • Daniel Burkacki
    • Robert Jankowski
    2019 Full text Applied Sciences-Basel

    During earthquakes, out-of-phase vibrations in adjacent buildings with limited distance may cause pounding between them. In recent years, the use of seismic isolation has expanded considerably as an effective approach to reduce seismic damage. However, the isolated building experiences large displacements during earthquakes, and there is a possibility of collisions with adjacent structures. The research on earthquake-induced pounding of base-isolated buildings has been mainly focused on interactions between low structures. In this paper, the influence of structural pounding on the response of medium-to-high-rise base-isolated buildings is investigated under different ground motions. The analysis has been focused on collisions between two insufficiently separated five-story and eight-story base-isolated and fixed base buildings aligned in three different configurations. The results of the study indicate that structural pounding may significantly increase the response of medium-to-high-rise base-isolated buildings during earthquakes. Moreover, substantial dependence of the structural behavior on the gap size between structures has been observed. The general trend shows the reduction in the pounding-involved response with the increase in the gap size value. The results indicate that the increase in the response of the base-isolated building is larger when the height of the structure is bigger. They also show that larger amplifications of peak accelerations of the upper stories can be expected due to collisions. On the other hand, the amplifications of the story shears have not shown any specific trend for different stories of the analyzed base-isolated building.

  • ECHOES REDUCTION DURING DIGITAL DATA TRANSMISSION IN HYDROACOUSTIC CHANNEL – LABORATORY EXPERIMENT
    • Agnieszka Czapiewska
    • Ryszard Studański
    • Andrzej Żak
    • Bogdan Żak
    2019 Full text

    The possibility of using a hydroacoustic channel for digital data transmission is very limited. This is due to the effect of multipath propagation of the emitted acoustic wave and the damping of the mechanical wave in this medium, which increase with frequency. The first of these phenomena results in inter-symbol interference disturbances in data transmission systems, including even hundreds of symbols. Due to the number of reflections and, at the same time, the long memory time of the hydroacoustic channel, it is particularly difficult to ensure communication in water of harbour areas, channels and straits with a rocky bottom etc. Therefore, our goal is to develop a method of echoes reduction in the hydroacoustic channel, which could be used in broadband underwater communication systems. The article presents researches carried out on method of echo reduction in digital data transmission in the hydroacoustic channel. The effectiveness of the method will be evaluated based on a comparison of the impulse responses of the hydroacoustic channel determined before and after the elimination of the echo. Moreover the variance of in-phase component as well as coefficient of variation will be determined for transmitted digital data and compared before and after using proposed method of echoes elimination. The researches will be carried out for different carrier frequencies of the test signals. In the research, we will use simulation methods and experimental research conducted in the laboratory conditions.

  • Ecological and Health Effects of Lubricant Oils Emitted into the Environment
    • Paulina Nowak
    • Karolina Kucharska
    • Marian Kamiński
    2019 Full text International Journal of Environmental Research and Public Health

    Lubricating oils used in machines with an open cutting system, such as a saw or harvester, are applied in forest areas, gardening, in the household, and in urban greenery. During the operation of the device with an open cutting system, the lubricating oil is emitted into the environment. Therefore, the use of an oil base and refining additives of petroleum origin in the content of lubricants is associated with a negative impact on health and the environment. The current legal regulations concerning lubricants applicable in the European Union (EU) assess the degree of biodegradability. Legislation permits the use of biodegradable oils at 60% for a period of 28 days. This means that, in practice, lubricating oil considered to be biodegradable can contain up to 50% of the so-called petroleum oil base. The paper aims to draw public attention to the need to reduce the toxicity and harmful eects, due to their composition, of lubricating oils emitted into the environment on health. The authors discuss the impact of petroleum oil lubricants on soils, groundwater, vegetation, and animals, and the impact of petroleum-origin oil mist on health. An overview of test methods for the biodegradability of lubricating oils is presented, including the Organization for Economic Cooperation and Development (OECD) 301 A–F, 310, and 302 A–D tests, as well as their standard equivalents. The current legal regulations regarding the use and control of lubricating oils emitted into the environment are discussed. Legal provisions are divided according to their area of application. Key issues regarding the biodegradability and toxicity of petroleum fractions in lubricating oils are also addressed. It is concluded that lubricating oils, emitted or potentially emitted into the environment, should contain only biodegradable ingredients in order to eliminate the negative impact on both the environment and health. Total biodegradability should be confirmed by widely applied tests. Therefore, a need to develop and implement low-cost and simple control procedures for each type of lubricating oil, ensuring the possibility of an indisputable conclusion about the presence and total absence of petroleum-derived components in oil, as well as the content of natural ingredients, occurs.

  • Economic migrations to Poland in 2008-2018
    • Robert Sterniński
    2019 Full text Zeszyty Naukowe Małopolskiej Wyższej Szkoły Ekonomicznej w Tarnowie

    The aim of the article is to present the stream and structure of economic migrants to Poland between 2008-2018. The first part presents economic migrations in its theoretical aspects, explaining the concept and presenting definitions. Then, the institutional and legal conditions of economic migration to Poland with particular emphasis on documents recquired by Polish labor market were presented i.e. work permits, seasonal work permits and declarations of entrusting work to a foreigner. The next part presents data on the number of issued statements and work permits, indicating the potential number of economic migrants. Data from the Social Insurance Institution regarding foreigners registered for retirement and disability insurance were also presented. Moreover data analysis and evaluation was performed. The article ends with a summary.

  • Economics of credit scoring management
    • Błażej Kochański
    2019

    Credit scoring models constitute an inevitable element of modern risk and profitability management in retail financial lending institutions. Quality,or separation power of a credit scoring model is usually assessed with the Gini coefficient. Generally, the higher Gini coefficient the better, as in this way a bank can increase number of good customers and/or reject more bad applicants. In the paper a simple simulation framework for analysis of microeconomics of credit scoring management is presented. The modeltakes into account competition among banks(there are 10 competing banks in the model), risk-based pricing (the banks differentiate prices based on their credit scoring models), “loan-shopping” practices by credit applicants(each applicant checks the price offered by three randomly selected banks). Such a setup enables us to perform a simulation where one of the banks improves the credit scoring model used and benefits from it. As the simulation shows, even small changes in Gini coefficient may lead to substantial improvement of bank’s standing measured by its profitability and market share.

  • Education of Logisticians in Poland: Problems and Prospects in Students’ Opinion
    • Nina Rizun
    • Pawłyszyn Irena
    • Ryzhkova Halina
    • Irena Pawłyszyn
    2019 Logistics and Transport

    Logistics is one of the key sectors of the Polish economy. Its value reflects not only its own capacity, but also the role it plays in ensuring the proper functioning of the entire economy. The rapid development of the industry and the highest demands on logistics solutions bring to the fore the problem of preparing a new generation of specialists in logistics. That is why the question of compliance to learning expectations of both students and the labour logistics market is so important, as well as the problems of efficiency and adequacy of training provided to students with the knowledge and skills to achieve the desired job, and the opportunities of Polish Universities’ graduates to work abroad. The objective of the paper was to identify the expectations of students who study Logistics at the Faculty of Engineering Management, Poznan University of Technology.

  • Efecto contagio en el uso del voto electrónico en Estonia: de las elecciones a otros niveles de la administración pública y la sociedad
    • Robert Krimmer
    • David Duenas Cid
    2019

    Estonia, cuarto país más pequeño de la Unión Europea tras Luxemburgo, Chipre y Malta, con una población que no alcanza el millón y medio de habitantes, ha sido en los últimos años objeto de atención mediática internacional por considerarlo the World’s more digital country (GREENWALD, 2018) , the first “Digital” Country (LUFKIN, 2017) o the Digital Republic (HELLER, 2017); así como uno de los referentes en el mundo académico en relación a la adopción de medidas de eGobernanza (ALVAREZ, HALL y TRECHSEL, 2009; KITSING, 2011; TOOTS, KALVET y KRIMMER, 2016). La razón de esta atención descansa en el modelo de administración pública digital diseñado y adoptado por esta República a partir de su última independencia en 1991.

  • Efektuacyjność modelu mentalnego przedsiębiorczości
    • Beata Krawczyk-Bryłka
    • Katarzyna Stankiewicz
    • Paweł Ziemiański
    • Michał Tomczak
    2019 Full text Przedsiębiorczość - Edukacja

    Artykuł prezentuje dwa modele przedsiębiorczości: tradycyjny (kauzalny) i efektuacyjny. Zgodnie z modelem kauzalnym najważniejszymi czynnikami sukcesu firmy jest strategiczne planowanie i konkurencyjność. W modelu efektuacyjnym znaczenie mają posiadane przez przedsiębiorcę zasoby, elastyczne reagowanie na szanse pojawiające się w otoczeniu i budowanie relacji biznesowych z otoczeniem. Celem artykułu jest ocena efektuacyjności mentalnego modelu przedsiębiorczości, czyli ocena czy i w jakim stopniu model mentalny przedsiębiorczości prezentowany przez badanych studentów jest koherentny z efektuacyjnym modelem przedsiębiorczości. Model efektuacyjny jest stosunkowo rzadko wykorzystywany w polskiej literaturze, co podkreśla wartość realizowanego celu. W przeprowadzonych badaniach nacisk położono na cztery elementy modelu mentalnego przedsiębiorczości: opracowanie strategii, wykorzystanie zasobów, postawy wobec ryzyka i wobec pozostałych uczestników rynku. Wykorzystano 39-itemowy kwestionariusz, w którym proszono studentów o ocenę, jak bardzo dane stwierdzenia odnoszą się do efektywnego przedsięwzięcia biznesowego. Wyniki wskazują, że modele mentalne studentów odpowiadają założeniom modelu tradycyjnego. Jedynie w odniesieniu do planowania strategii integrują one elementy obu modeli. Modele mentalne mężczyzn w odniesieniu do strategii firmy są bardziej efektuacyjne niż kobiet. Kobiety bardziej efektuacyjnie myślą o budowaniu relacji biznesowych. Wyniki badań posłużyły do opracowania rekomendacji dla kształtowania efektuacyjnych postaw przedsiębiorczych studentów, szczególnie w zakresie koopetycji, traktowania ryzyka jako hamulca bezpieczeństwa i koncentrowania się na posiadanych zasobach.

  • Efektywność działania środków przeciwstarzeniowych w procesie przyśpieszonego starzenia cieplnego
    • Paulina Kasprzyk
    • Daniel Bartkowski
    • Marcin Włoch
    • Janusz Datta
    2019 Elastomery

    Przedmiotem przedstawionych badań są wulkanizaty kauczuku naturalnego i butadienowo-styrenowego. Celem pracy było zbadanie efektywności działania środków przeciwstarzeniowych w procesie przyspieszonego starzenia cieplnego (w czasie 7 i 14 dni w temperaturze 70°C). Do badań wykorzystano dwie substancje przeciwstarzeniowe: komercyjnie dostępny przeciwutleniacz IPPD (N–fenylo-N′-izopropylo-p-fenylenodiamina) oraz ekologiczny przeciwutleniacz K (aminowo-amidowa pochodna kalafonii). Struktura chemiczna próbek referencyjnych oraz wulkanizatów po procesie starzenia została zidentyfikowana z wykorzystaniem analizy spektroskopowej w podczerwieni (FTIR). Zbadano również właściwości mechaniczne wulkanizatów przy statycznym rozciąganiu, twardość, elastyczność przy odbiciu oraz ścieralność. Przeprowadzone badania dowiodły wysokiej efektywności działania przeciwutleniacza K, szczególnie w przypadku wulkanizatów opartych na kauczuku naturalnym