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Gdańsk University of Technology

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  • EXTREME RAINFALLS AS A CAUSE OF URBAN FLASH FLOODS; A CASE STUDY OF THE ERBIL-KURDISTAN REGION OF IRAQ
    • Andam Mustafa
    • Hadi Muhammed
    • Michał Szydłowski
    2019 Full text Acta Scientiarum Polonorum Formatio Circumiectus

    Aim of the study The current paper aims to give a detailed evaluation and analysis of some extreme rainfall events that happened in the last decade in terms of spatial and temporal rainfall distribution, intensity rate, and exceedance probability. Moreover, it examines the effects of each analysed aspect on the resulting flash floods in the studied area. Material and methods In their glossary of meteorology, American Meteorology Society (AMS) subdivided rainfall intensity types into four groups (light, moderate, heavy, and violent). Also, for estimating the exceedance probability, lognormal distribution was applied as a statistical model of the precipitation probability distribution function. Results and conclusions Out of six episodes, five of the analysed events were classified as heavy rainfall. However, the duration of those heavy rainfall events was not more than two hours. Four events of maximum daily rainfall (for a 39-year dataset) were rated at 1–10% of exceedance probability. To conclude, the current study can be an initial step in modelling hydrological events in the studied area, and in the process of transforming precipitation into the outflows of urban basins in the future.

  • Fabrication and Structural Properties of LaNb 1‐x As x O 4 Ceramics
    • Sebastian Wachowski
    • Bartosz Kamecki
    • Piotr Winiarz
    • Kacper Dzierzgowski
    • Michał Jurkowski
    • Jaroslav Dzisevič
    • Aleksandra Mielewczyk-Gryń
    • Maria Gazda
    2019 ChemistrySelect

    Lanthanum niobate substituted with arsenic was synthesized by three methods: solid state reaction from binary oxides and two different methods combining co-precipitation and solidstate reaction. In the first of the combined methods LaNb1- xAsxO4 was synthesized from LaAsO4, obtained from coprecipitation method, and lanthanum and niobium oxides. In the second LaNbO4 was first synthesized from binary oxides and then mixed with LaAsO4 and fired in the second step to obtain the final material. Single phase materials could not be synthesized via solid-state synthesis, whilst it was possible with both of the combined methods. Structural parameters of the materials obtained with both methods were similar what shows that they do not relate to the synthesis method. Ceramics obtained with both combined methods were dense, however, the density of the ceramics formed from LaAsO4 and LaNbO4 was higher.

  • Fabrication methods of smart composite coatings - review
    • Łukasz Pawłowski
    • Michał Bartmański
    • Andrzej Zieliński
    2019 Full text European Journal of Medical Technologies

    Postoperative bacterial infections are one of the main reasons for unsuccessful implantation of long-term implants. The development of bacterial infection requires antibiotic therapy, in extreme cases a reimplantation procedure is necessary. In order to provide materials for implants with antibacterial properties, they are subjected to modifications to create a coating that will release the drug substance, when the inflammation occurs. Significant interest is now gained by the so-called smart polymers, that react to the stimuli from the external environment such as pH change, temperature change, the influence of UV-VIS radiation or interaction of electric and magnetic fields. When designing drug delivery systems, the characteristics of the inflamed tissue may be taken into account, because they are characterized by increased temperature and reduced pH. It would, therefore, be reasonable to create biopolymer coatings that under these conditions degrade and release the drug substance. However, the problem is the controlled release of the drug substance trapped in the biopolymer matrix. This review paper presents most often used methods of smart biopolymer coatings production, which release the drug substance in a controlled manner. Methods such as electrophoretic deposition, dip-coating, spin-coating, and layer-by-layer are discussed, including process parameters, steps of the coating production, possible post-processing and examples of smart coatings produced using these methods. Each of these methods offers a wide range of process parameters, by changing these parameters it is possible to fine-tune the properties of the coatings produced to the desired values. Extensive research is needed to determine the optimal process parameters that will allow the production of coatings with the desired properties.

  • Fading Analysis in Off-Body Channels in a Straight Metallic Corridor in a Passenger Ferry Environment
    • Paweł Tomasz Kosz
    • Sławomir Ambroziak
    • Luis M. Correia
    • Jacek Stefański
    2019

    This paper presents a fading analysis for Body Area Networks off-body communications at 2.45 GHz in a passenger ferry environment. The results are based on measurements performed for dynamic scenarios in a straight metallic corridor. Two components, extracted from instantaneous system loss values, have been analysed: small- and large-scales fading, separately for each scenario. Well-known probability distribution functions have been fitted to the empirical distributions by using Goodness of Fit tests. The slow fading component is best modelled by the Lognormal Distribution, with 0 dB mean and [1.22, 2.88] dB standard deviation parameters, while the fast fading one is by the Nakagami-m Distribution with [0.78, 0.91] shape and [1.9, 2.18] scale parameters.

  • Fake News: Possibility of Identification in Post-Truth Media Ecology System
    • Jan Kreft
    2019 Full text Zarządzanie Mediami

    The main aim of the article is identification of the attitudes towards the processes of identification and verification of fake news in the environment of digital media. The subject of the research refers to the users’ attitudes towards fake news. As indicated by the research, the attitudes towards fake news are not unambiguous. About 2/3 of the respondents claim that they are not able to distinguish fake news from true information; only every twelfth respondent declares that they know tools for verification of information, although the research survey has been carried out among students of media management, journalism and marketing – students who deal with information in social media.

  • Fake News: Possibility of Identification in Post-Truth Media Ecology System
    • Jan Kreft
    • Monika Hapek
    2019 Full text

    Information comes as basic good which affects social well-being. A modern society and a modern state – its administration, education, culture, national economy and armed forces – cannot function efficiently without a rationally developed field of information. The quality of the functioning of that system depends on a specific feature of information, that is namely: its reliability which makes it possible for us to evaluate accuracy, completeness, valence and trust towards information. A part of information conveyed in social media is fake news that is namely: distorted signals not correlated with the truth, which may mislead their recipients. Such information comes as an element of info-environment defined by the term of post-truth. The main aim of the article is identification of the attitudes towards the processes of identification and verification of fake news in the environment of digital media. The subject of the research refers to the users’ attitudes towards fake news. As indicated by the research, the attitudes towards fake news are not unambiguous. About 2/3 of the respondents claim that they are not able to distinguish fake news from true information; only every twelfth respondent declares that they know tools for verification of information, although the research survey has been carried out among students of media management, journalism and marketing – students who deal with information in social media

  • Fast Basis Function Estimators for Identification of Nonstationary Stochastic Processes
    • Maciej Niedźwiecki
    • Marcin Ciołek
    • Artur Gańcza
    2019

    The problem of identification of a linear nonsta-tionary stochastic process is considered and solved using theapproach based on functional series approximation of time-varying parameter trajectories. The proposed fast basis func-tion estimators are computationally attractive and yield resultsthat are better than those provided by the local least squaresalgorithms. It is shown that two important design parameters –the number of basis functions and the size of the local analysisinterval – can be selected on-line in an adaptive way.

  • Fast geometry scaling of miniaturized microwave couplers with power split correction
    • Sławomir Kozieł
    • Adrian Bekasiewicz
    2019 INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING

    Redesigning a microwave circuit for various operating conditions is a practically important yet challenging problem. The purpose of this article is development and presentation of a technique for fast geometry scaling of miniaturized microwave couplers with respect to operating frequency. Our approach exploits an inverse surrogate model constructed using several reference designs that are optimized for a set of operating frequencies within a range of interest. For the sake of computational efficiency, the reference designs are obtained for an equivalent network model of the coupler. The surrogate directly predicts the optimum values of geometry parameters of the structure at hand corresponding to a requested operating frequency. By introducing appropriate correction, the model allows for coupler scaling at the EM simulation model level. Because the surrogate does not carry information about the power split ratio of the coupler, an additional analytical corrective procedure is developed to ensure an equal power split of scaled structure. The computational cost of the scaling procedure corresponds to only two EM analyses of the circuit at hand (including both correction steps). The operation and performance of our technique is demonstrated using a compact microstrip rat‐race coupler scaled for the operating frequency range of 0.5‐2.5 GHz. Experimental validation is also provided.

  • Fast surrogate-assisted frequency scaling of planar antennas with circular polarisation
    • Sławomir Kozieł
    • Adrian Bekasiewicz
    2019 IET Microwaves Antennas & Propagation

    In this work, the problem of computationally efficient frequency scaling (re-design) of circular polarisation antennas is addressed using surrogate-assisted techniques. The task is challenging and requires the identification of the optimum geometry parameters to enable the operation of the re-designed structure at a selected (required) centre frequency. This involves handling several performance figures such as the antenna gain, the impedance bandwidth, as well as the axial ratio bandwidth. The design technique described here involves two types of surrogate models: an inverse surrogate (utilised to find the initial design) and a forward surrogate of the structure response sensitivities, necessary to realise post-scaling design correction. The entire re-design process is fast and only requires a few full-wave electromagnetic simulations of the antenna. The proposed dimension scaling method is demonstrated using a patch antenna with circular polarisation fed through a branch-line coupler. The structure is re-designed within the operating frequency range of 4.5–6.5 GHz. Numerical results are validated experimentally.

  • Fast tolerance-aware design optimization of miniaturized microstrip couplers using variable-fidelity EM simulations and re-sponse features
    • Sławomir Kozieł
    • Adrian Bekasiewicz
    2019 ENGINEERING COMPUTATIONS

    Manufacturing tolerances and other types of uncertainties may considerably affect operation and performance of microwave components and systems. Quantification of these effects is therefore an important part of the design process. It is even more important to obtain designs whose sensitivity to parameter deviations is reduced as much as possible. All of these require statistical analysis carried out at the level of electromagnetic (EM) simulation models, which may be prohibitively expensive when executed directly, e.g., through Monte Carlo simulations. In this work, a technique for fast yield optimization of compact microstrip couplers is proposed. Our methodology involves variable-fidelity EM models, local surrogates constructed using a response feature approach, as well as a sequential approximation optimization framework. A combination of these tools permits yield optimization at a remarkably low cost corresponding to less than a dozen of high-fidelity EM analyses of the circuit under design. The proposed approach is demonstrated using a miniaturized equal-split rat-rate coupler operating at 1 GHz. Reliability of results is validated using direct (high-fidelity) Monte Carlo simulations of the initial and optimized designs.

  • FE analysis of support-specimen interaction of compressive experimental test
    • Krzysztof Wołoszyk
    • Yordan Garbatov
    2019

    The objective of this work is to investigate the support-specimen interaction during the compressive experimental testing of stiffened plates. The interaction is analyzed employing the nonlinear Finite Element Method using the commercial software ANSYS. The connection between the stiffened plate and testing supports is modelled with the use of contact elements, where several possible interaction scenarios are investigated, and their impact on the ultimate strength is evaluated. The sensitivity of the modelling of the testing support structure to the boundary conditions as generated by the finite element model and the structural behavior of stiffened plates during the test are also investigated, and several conclusions are derived.

  • FEA analysis of the multicell piezoelectric motor
    • Roland Ryndzionek
    • Łukasz Sienkiewicz
    • Michał Michna
    • Filip Kutt
    • Grzegorz Kostro
    • Mieczysław Ronkowski
    2019 Full text

    The presented paper concerns a design, modeling and chosen tests of the prototype multicell piezoelectric motor (MPM). The principle of operation based on three independent traveling wave actuators is presented. The main materials and technologies used in the fabrication process are described. The structure of the motor is modeled using static and modal FEM analysis. The process of traveling wave generation in the MPM structure is demonstrated. Finally, the main results of the simulation are validated by measurements of MPM prototype. The natural frequencies of three actuators are measured along with the corresponding displacements at two locations.

  • Feedline Alterations for Optimization-Based Design of Compact Super-Wideband MIMO Antennas in Parallel Configuration
    • Muhammad ul Haq
    • Sławomir Kozieł
    2019 IEEE Antennas and Wireless Propagation Letters

    This letter presents a technique for size reduction of wideband multiple-input-multiple-output (MIMO) antennas. Our approach is a two-stage procedure. At the first stage, the antenna structure is modified to improve its impedance matching. This is achieved through incorporation of an n-section tapered feedline, followed by reoptimization of geometry parameters. Reducing the maximum in-band reflection well beyond the acceptance level of -10 dB creates room for size reduction, realized in the second stage as explicit footprint area minimization with the constraints imposed on the maximum in-band reflection level (|S 11 | ≤ -10 dB) and element isolation (|Sε| ≤ -20 dB). The technique is generic and can be applied to various monopole-based MIMO structures. It is validated using two antenna structures operating from 2.8 to 20 GHz. Various complexities of the tapered lines are also investigated, from n = 1 to 5. To the best of the authors' knowledge, the obtained footprints (452 and 546 mm 2 , respectively) are the smallest to date while ensuring acceptable performance, specifically impedance matching, isolation, envelope correlation coefficient (<;0.005), and diversity gain (>9.99 dB).

  • Fermentative Conversion of Two-Step Pre-Treated Lignocellulosic Biomass to Hydrogen
    • Karolina Kucharska
    • Hubert Cieśliński
    • Piotr Rybarczyk
    • Edyta Słupek
    • Rałał Łukajtis
    • Katarzyna Wychodnik
    • Marian Kamiński
    2019 Full text Catalysts

    Fermentative hydrogen production via dark fermentation with the application of lignocellulosic biomass requires a multistep pre-treatment procedure, due to the complexed structure of the raw material. Hence, the comparison of the hydrogen productivity potential of different lignocellulosic materials (LCMs) in relation to the lignocellulosic biomass composition is often considered as an interesting field of research. In this study, several types of biomass, representing woods, cereals and grass were processed by means of mechanical pre-treatment and alkaline and enzymatic hydrolysis. Hydrolysates were used in fermentative hydrogen production via dark fermentation process with Enterobacter aerogenes (model organism). The differences in the hydrogen productivity regarding different materials hydrolysates were analyzed using chemometric methods with respect to a wide dataset collected throughout this study. Hydrogen formation, as expected, was positively correlated with glucose concentration and total reducing sugars amount (YTRS) in enzymatic hydrolysates of LCMs, and negatively correlated with concentrations of enzymatic inhibitors i.e., HMF, furfural and total phenolic compounds in alkaline-hydrolysates LCMs, respectively. Interestingly, high hydrogen productivity was positively correlated with lignin content in raw LCMs and smaller mass loss of LCM after pre-treatment step. Besides results of chemometric analysis, the presented data analysis seems to confirm that the structure and chemical composition of lignin and hemicellulose present in the lignocellulosic material is more important to design the process of its bioconversion than the proportion between the cellulose, hemicellulose and lignin content in this material. For analyzed LCMs we found remarkable higher potential of hydrogen production via bioconversion process of woods i.e., beech (24.01 mL H2/g biomass), energetic poplar (23.41 mL H2/g biomass) or energetic willow (25.44 mL H2/g biomass) than for cereals i.e., triticale (17.82 mL H2/g biomass) and corn (14.37 mL H2/g biomass) or for meadow grass (7.22 mL H2/g biomass).

  • FIBRE-OPTIC SENSOR FOR SIMULTANEOUS MEASUREMENT OF THICKNESSAND REFRACTIVE INDEX OF LIQUID LAYERS
    • Marcin Marzejon
    • Katarzyna Karpienko
    • Adam Mazikowski
    • Małgorzata Szczerska
    2019 Full text Metrology and Measurement Systems

    In this paper, we present a fibre-optic sensor for simultaneous measurement of refractive index and thickness of liquid layers. We designed an experimental low-coherence setup with two broadband light sources and an extrinsic fibre-optic Fabry–Pérot interferometer acting as the sensing head. We examined how the refractive index of a liquid film and its thickness affect spectrum at the output of a fibre-optic interferometer. We performed a series of experiments using two light sources and only one sensing head. The spectra were collected in ranges of 1220÷1340 nm and 1500÷1640 nm. The obtained results show that using two spectra recorded simultaneously for two wavelength ranges enables to determine thickness in a range of 50÷500 µm, and refractive index of a liquid film in a range of 1:00÷1:41 RIU using only one sensing head.

  • Fighting Administrative Corruption with Digital Government in Sub-Saharan Africa
    • Yelkal Walle
    • Tomasz Janowski
    • Elsa Estevez
    2019 Full text

    Administrative corruption is a pervasive problem and a major threat to economic and social development around the world, especially in Sub-Saharan Africa which lags behind other regions in various development indicators and is seen as one of the most corrupt regions globally. This paper examines a hypothesis that digital government – the use of digital technology to transform public administration organizations and their relationships with citizens, businesses and each other – helps reduce administrative corruption in Sub-Saharan Africa. To this end, the paper relates the United Nation’s e-Government Development Index (EDI) and the Transparency International’s Corruption Perception Index (CPI) for 45 countries in the region in the period from 2012 to 2016, performing linear regression with EDI as an independent and CPI as a dependent variable. The estimated results show that the effects of digital government adoption on corruption reduction are statistically significant, with 37% of corruption reduction due to digital government development. The paper further explores the nature of this relationship using the case of Ethiopia, whose performance according to the EDI and CPI indexes improved slightly over the 2012-2016 period. As part of this case, the paper examines common applications such as e-procurement or e-tax that cut horizontally across ministries. Our findings suggest that the adoption of digital government has the potential for reducing administrative corruption in Sub-Saharan Africa but realizing such potential require strengthening of law enforcement and anti-corruption institutions, and political will.

  • Filozofia sieci 5G - radioinformatyka i wirtualizacja. Część 2. Wirtualny system 5G.
    • Sławomir Gajewski
    • Małgorzata Gajewska
    2019 Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

    Przedstawiono najważniejsze właściwości sieci 5G z punktu widzenia istoty jej działania. Uporządkowano najistotniejsze pojęcia służące do opisu sieci 5G, zwłaszcza w kontekście rozwiązań softwarowych, wirtualizacji sieci oraz jej architektury fizycznej i funkcjonalnej. Wprowadzono i zdefiniowano wiele pojęć wynikających z nowej ery rozwoju radiokomunikacji, w tym pojęcie radioinformatyki, systemu radioinformatycznego, sieci radioinformatycznej. Uporządkowano i zdefiniowano główne elementy architektury sieci 5G zgodnie z przebiegiem standaryzacji oraz wskazano sposób integracji sieci 5G z 4G. Pierwsza część artykułu pt. Radioinformatyczny system 5G dotyczy w szczególności nowej nomenklatury koniecznej do przyjęcia w radiokomunikacji. Część druga pt. Wirtualny system 5G będzie natomiast dotyczyła problemu wirtualizacji w sieci 5G.

  • Finding small-width connected path decompositions in polynomial time
    • Dariusz Dereniowski
    • Dorota Osula
    • Paweł Rzążewski
    2019 Full text THEORETICAL COMPUTER SCIENCE

    A connected path decomposition of a simple graph $G$ is a path decomposition $(X_1,\ldots,X_l)$ such that the subgraph of $G$ induced by $X_1\cup\cdots\cup X_i$ is connected for each $i\in\{1,\ldots,l\}$. The connected pathwidth of $G$ is then the minimum width over all connected path decompositions of $G$. We prove that for each fixed $k$, the connected pathwidth of any input graph can be computed in polynomial-time. This answers an open question raised by Fedor V. Fomin during the GRASTA 2017 workshop, since connected pathwidth is equivalent to the connected (monotone) node search game.

  • First Copper(I) and Silver(I) Complexes Containing Phosphanylphosphido Ligands
    • Aleksandra Ziółkowska
    • Sandra Brauer
    • Łukasz Ponikiewski
    2019 Full text ZEITSCHRIFT FUR ANORGANISCHE UND ALLGEMEINE CHEMIE

    Three new complexes with phosphanylphosphido ligands, [Cu4{μ2-P(SiMe3)-PtBu}4](1), [Ag4{μ2-P(SiMe3)-PtBu2}4](2) and [Cu{η1-P(SiMe3)-PiPr2}2]–[Li(Diglyme)2] (3) were synthesized and structurally characterized by X-ray diffraction, NMR spectroscopy, and elemental analysis. Complexes 1 and 2 were obtained in the reactionsof lithium derivative of diphosphane tBu2P-P(SiMe3)Li·2.7THF withCuCl and [iBu3PAgCl]4, respectively. The X-ray diffraction analysis revealed that the complexes1 and 2 present macrocyclic, tetramericform with Cu4P4and Ag4P4core. Complex 3 was prepared in thereaction of CuCl with a different derivative of lithiated diphosphane iPr2P-P(SiMe3)Li·2(Diglyme). Surprisingly, the X-ray analysis of 3 revealed that in this reaction instead of the tetramer the monomericform, ionic complex [Cu{η1-P(SiMe3)-PiPr2}2]–[Li(Diglyme)2] was formed.

  • First report on echinocandin resistant Polish Candida isolates
    • Martyna Mroczyńska
    • Anna Brillowska-Dąbrowska
    2019 Full text Acta Biochimica Polonica

    Purpose: Candida spp. are ranked as one of the four major causative agents of fungal infections. The number of infections caused by Candida species resistant to fluconazole, which is applied as the first line drug in candidiasis treatment, increases every year. In such cases the application of echinocandin is necessary. Echinocandin susceptibility testing has become a routine laboratory practice in many countries due to the increasing frequency of clinical failures during treatment with these drugs. Methods: We performed anidulafungin, micafungin and caspofungin susceptibility testing according to the microdilution broth method on 240 Candida isolates collected in Polish hospitals. Results: We identified 12 isolates resistant to all echinocandins within 240 examined isolates. Moreover, 6 of the examined samples were identified as rare Candida species and among them we observed very high echinocandin MIC values. Conclusion: Our research proves that in Poland there is a problem of echinocandin resistance. Moreover, we identified two species of Candida which are rare causative agents of human infections, and there was no reported incidence of such infections in Poland until now.

  • Flexural buckling and post-buckling of columns made of aluminium alloy
    • Czesław Szymczak
    • Marcin Kujawa
    2019 EUROPEAN JOURNAL OF MECHANICS A-SOLIDS

    The paper concerns flexural buckling and initial post-buckling of axially compressed columns made of aluminium alloy described by the Ramberg-Osgood relationship. The non-linear differential equation of the problem is derived using the stationary total energy principle and the assumptions of classical beam theory within a finite range. The approximate analytical solution of the equation leading to the buckling loads and initial post-buckling equilibrium path is determined by means of the perturbation approach. Numerical examples dealing with simply supported and clamped I-columns are presented, the effect of the material non-linearity on the critical loads and initial post-buckling behaviour in comparison to linear one is discussed too. The analytical results are compared with the FEM solutions to present a good agreement.

  • Flood Security Strategy - Case Studies from Gdańsk Region
    • Andrzej Lewandowski
    • Piotr Kowalski
    • Wojciech Szpakowski
    2019

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  • Floodplain inundation Mapping using SAR Scattering Coefficient Thresholding and Observed Discharge Data
    • Tomasz Berezowski
    • Tomasz Bieliński
    • Jakub Osowicki
    2019 Full text

    Inundation area time series are important for wetlands monitoring and hydrological model validation. This study is conducted in Biebrza floodplain, which is a natural wetland with complex inundation generation processes. In order to map 2014-2018 series of inundation in the floodplain we test our automatic thresholding method on Sentinel 1 data. The threshold value is optimized using correlation of the inundation area with observed discharge at the floodplain outlet. The inundation maps match well the MODIS 500m reflectance data used as a reference, whereas, the total inundated area per Sentinel 1 image match well the observed discharge pattern. Unfortunately, this approach was unable to identify inundation in remote parts of the floodplain, what may have few reasons and needs further investigation.

  • Flow Boiling in Minigap in the Reversed Two-Phase Thermosiphon Loop
    • Michał Klugmann
    • Paweł Dąbrowski
    • Dariusz Mikielewicz
    2019 Full text ENERGIES

    The paper presents the results of experimental investigations of a model of a heat exchanger featuring a minigap, which is perceived as an evaporator for an inverted thermosiphon. The system works with a single component test fluid. The tested evaporator generates pumping power in the test loop in a way similar to the mammoth pump. The tests regarded a module of the heat exchanger, consisting of a hot leg and a cold leg with the width by the length of 0.1 × 0.2 m, heated by a uniform heat flux. In the tests, the minigaps of 1, 2 and 3 mm were formed. Two fluids, namely, distilled water and ethanol, were tested in the facility. Two-phase flow structures for both working fluids and various operational parameters, together with comprehensive visualization material, are presented. The specifics of pressure changes and its influence on operating parameters and flow structure are discussed.

  • Flow maldistribution and its mitigation in mini heat exchangers
    • Paweł Dąbrowski
    • Michał Klugmann
    • Dariusz Mikielewicz
    2019

    In the present paper, a detailed numerical investigation has been carried out to analyze the flow maldistribution in 50 parallel 1 mm x 1 mm rectangular minichannels and 1 mm depth minigap section with rectangular, trapezoidal, triangular or concave mani-folds in Z-type flow configuration (16 different cases). The working medium was ethanol and the mass flow rate was 5×10-4 kg/s. Both sections was heated from the bottom side. Heat flux of 10 000 W/m2 and 5 000 W/m2 was applied to the minichannel and minigap section respectively. It provides an equal heat flow rate of about 50 W for both types of the sections. A novel approach for the mitigation of non-uniformity has been proposed introducing threshold at the entrance of the minigeometry section. The maldistribution coefficient can be reduced about twice in the minigap section or about three times in the minichannel section with the 0.5 mm threshold as compared to the conventional arrangement without threshold. Authors analyzed velocity profile and temperature profile over the heat exchanger’s surface. Reduction of maldistribution results in lower maximum temperature over the surface. The distribution is more uniform in minichannel section than in minigap section. This is due to a two-dimensional flow over a minigap in comparison to one-dimensional flow in channels. To obtain uniform distribution of fluid and hence uniform temperature profile, flow should be stabilized al-ready at the inlet manifold, at the entrance to the minichannel or minigap section.

  • Folate/homocysteine metabolism and lung cancer risk among smokers
    • Anna Stanisławska-Sachadyn
    • Joanna Borzyszkowska
    • Michał Krzemiński
    • Alicja Janowicz
    • Rafał Dziadziuszko
    • Jacek Jassem
    • Witold Rzyman
    • Janusz Limon
    2019 Full text PLOS ONE

    Background: Folate and homocysteine are involved in DNA synthesis and methylation processes, which are deregulated during carcinogenesis. Objectives: The aim of this study was to assess the relationship between folate/homocysteine concentrations, the functional polymorphisms of folate/homocysteine genes and lung cancer risk among cigarette smokers. Study design: The study included 132 lung cancer patients and 396 controls from northern Poland, matched by sex, age and smoking status. The median cigarette pack-years of smoking among both cases and controls was 30.0. Serum, red blood cell (RBC) folates and serum homocysteine concentrations were measured. The genotypes in selected polymorphic sites of the MTHFR, CBS, SHMT1, MTHFD1, MTRR, MTR, TYMS DHFR, TCN2, and SLC19A1 genes were determined. All study participants underwent scanning with low-dose computed tomography. Results: Serum folate concentrations above the median (> 17.5 nmol/l among the healthy controls) were associated with an increased lung cancer risk (odds ratio [OR], 1.54, 95% confidence intervals [CI], 1.04-2.29, P= 0.031). An analogous trend was observed when the population was analysed after subdivision according to RBC folate concentrations, that is, above a value of 506.5 nmol/l (OR, 1.53; 95% CI, 0.95-2.47; P=0.084). Additionally, in a subset of women, an increased risk of lung cancer development was associated with the SLC19A1 c.80AA genotype (c.80AA versus GG OR, 3.14; 95% CI, 1.32-7.46; P= P=0.010). Conclusion: These results suggest that, in the population consisting of heavy smokers, high folate levels add to the cancerogenic effect of smoking.

  • Follow the Light. Where to search for useful research information
    • Karolina Zielińska-Dąbkowska
    2019 Full text ARC Lighting In Architecture

    Architectural Lighting Design (ALD) has never been a standalone professional discipline. Rather, it has existed as the combination of art and the science of light. Today, third generation lighting professionals are already creatively intertwining these fields, and the acceleration in scientific, technological and societal studies has only increased the need for reliable multidisciplinary information. Therefore, a thorough re-examination of all aspects of ALD and how it relates to those particular changes is an urgent necessity. Further research is required to develop a new body of knowledge about ALD so that lighting professionals can improve their expertise in the field and receive better remuneration for their complex work. In the near future, we should be aiming for professional recognition as experts and join other recognised professions such as: architects, doctors, dentists, lawyers, engineers etc. While lighting designers (LD) need to constantly update and reexamine their knowledge, they face two dilemmas. First, WHERE should they search to obtain useful information on lighting in related fields? And secondly, HOW should they successfully evaluate the viability of this information in a time of “Google-isation”, Wikipedia, “lobbying” and data manipulation.

  • Force transfer and stress distribution in short cantilever deep beams loaded throughout the depth with a various reinforcement
    • Anna Kopańska
    • Krystyna Nagrodzka-Godycka
    2019

    Deep beams used as the main reinforced concrete structural elements which taking over the load and stiffening construction are often found in high-rise buildings. The architecture of these buildings is sometimes sophisticated and varied, arouse the admiration of the majority of recipients, and thus causing an engineering challenge to correctly design the structural system and force transfer. In such structures is important to shape the reinforcement in order to make the best use of reinforcing steel for taking over the load and minimize the crack widths. Despite the wide use of these elements, they are still not covered by the relevant design codes. In the current technical literature there is little information on the dimensioning of reinforced concrete cantilever deep beams or deep beams with overhangs and only few based on experimental research. This paper presents the results of experimental investigations of two reinforced concrete cantilever deep beams with shear slenderness lk / H = 0.3 under static load distributed on the entire height. The research elements were part of the spatial reinforced concrete deep beam systems, consisting of a transversal deep beam and suspended on it the longitudinal deep beam with cantilever. Reinforced concrete deep beam joints had various reinforcements. The article presents results on steel effort and force distribution in the reinforcement of short cantilever deep beam indirectly loaded. The effectiveness of the mixed reinforcement in both tested cantilever deep beams, as referred to the design recommendation proposed in the published papers is also verified. © Federation Internationale du Beton (fib) - International Federation for Structural Concrete, 2019.

  • FORECASTING EXCHANGE RATES IN THE PROCESS OF THE ASSESSMENT OF CONSUMER RISK BANKRUPTCY IN CENTRAL EUROPE
    • Tomasz Korol
    2019

    This paper focuses on the issue of forecasting the fluctuation of exchange rates as part of the early warning system against the risk of consumer bankruptcy. The author identified the main macroeconomic factors affecting the level of bankruptcies for households in Poland. The fluctuation of exchange rates, which directly affects the deterioration of the economic situation of borrowers who have opened credit accounts in a foreign currency and indirectly affects the cost of living of all consumers in the country, is one of the significant macroeconomic factors. That is why the main objective of the presented research is to investigate the effectiveness of fuzzy sets in predicting the volatility of two currency pairs (PLN/CHF and PLN/USD). The models created will be part of a system of models aimed at forecasting the risk of consumer bankruptcy in Poland. The results demonstrate the high predictive properties of fuzzy sets in forecasting the volatility of analyzed currency pairs.

  • Formalno-prawne uwarunkowania rozwoju mieszkalnictwa w Polsce w aspekcie eksploatacji mieszkalnych jednistek pływających
    • Emilia Miszewska
    • Maciej Niedostatkiewicz
    2019

    Artykuł zawiera analizę sytuacji prawnej obiektów jakimi są Domy Na Wodzie oraz konsekwencji jakie powodują dla właścicieli aktualne zapisy najważniejszych Ustaw z nimi związanych tzn.: ustawy Prawo budowlane, ustawy o gospodarce nieruchomościami, Kodeksu cywilnego oraz Prawa wodnego. W pracy opisano światowe trendy osadnictwa na wodzie i porównano do sytuacji mieszkalnictwa na wodzie w Polsce. Na podstawie doświadczeń innych krajów oraz w oparciu o przepisy krajowe, opracowano i zaproponowano autorską definicję dla Domów Na Wodzie, (DNW) nazwanych przez autorów Mieszkalnymi Jednostkami Pływającymi (MJP). Ponadto podjęto próbę usystematyzowania wymagań i rozwiązań części problemów formalno-prawnych jakie w fazie eksploatacji dotyczą właścicieli MJP.

  • Formation of Protein Networks between Mucins: Molecular Dynamics Study Based on the Interaction Energy of the System
    • Natalia Kruszewska
    • Piotr Bełdowski
    • Piotr Weber
    • Steven Yuvan
    • Marcin Drechny
    • Marcin Kośmieja
    2019 Full text ENERGIES

    Molecular dynamics simulations have been performed for a model aqueous solution of mucin. As mucin is a central part of lubricin, a key component of synovial fluid, we investigate its ability to form cross-linked networks. Such network formation could be of major importance for the viscoelastic properties of the soft-matter system and crucial for understanding the lubrication mechanism in articular cartilage. Thus,the inter- and intramolecular interaction energies between the residues of mucin are analyzed. The results indicate that the mucin concentration significantly impacts its cross-linking behavior. Between 160 g/L and 214 g/L, there seems to be a critical concentration above which crowding begins to alter intermolecular interactions and their energies. This transition is further supported by the mean squared displacement of the molecules. At a high concentration, the system starts to behave subdiffusively due to network development. We also calculate a sample mean squared displacement and p-variation tests to demonstrate how the statistical nature of the dynamics is likewise altered for different concentrations.

  • Fotokatalityczna degradacja zanieczyszczeń środowiskowych
    • Joanna Mioduska
    • Anna Zielińska-Jurek
    • Jan Hupka
    2019 Nowa Energia

    Fotokataliza uznawana jest za metodę z rosnącym potencjałem do usuwania zanieczyszczeń organicznych i nieorganicznych - zarówno z fazy wodnej, jak i gazowej. Liczba publikacji z ostatnich pięciu lat związana z tematyką fotokatalizy osiąga ponad 4000 rocznie, wg bazy danych Web of Science (2019 r.). Szczególny potencjał fotokatalizy tkwi w możliwości usuwania zanieczyszczeń uporczywie zalegających w środowisku, których źródłem są ścieki przemysłowe i komunalne.

  • Fractional Order Circuit Elements Derived from Electromagnetism
    • Tomasz Stefański
    • Jacek Gulgowski
    2019

    In this paper, derivations of fractional-order (FO) circuit-element equations from electromagnetism are presented. Whilst many papers are devoted to FO modelling of electrical circuits, there are no strong foundations for such an approach. Therefore, we investigate relations between the FO electromagnetism and the FO circuit theory. Our derivations start from quasi-static (QS) approximations of Maxwell's equations in media with FO constitutive relations. Hence, FO lumped-element equations are derived which are supported by an approximate applicability condition. If the FO capacitor/inductor satisfies the derived condition, then the energy of the magnetic/electric field is negligible in comparison to the energy of the electric/magnetic field in the considered FO element. Then, we demonstrate that FO lumped-element parameters can be derived assuming the equality of electromagnetic power flowing into the circuit element and calculated as the current and voltage product. The obtained results support researchers and engineers employing FO modelling in electrical and electronics engineering.

  • Fracture evolution in concrete compressive fatigue experiments based on X-ray micro-CT images
    • Łukasz Skarżyński
    • Ireneusz Marzec
    • Andrzej Tejchman-Konarzewski
    2019 Full text INTERNATIONAL JOURNAL OF FATIGUE

    Artykuł omawia ewolucje pękania w betonie podczas cyklicznego ściskania betonu. Przestrzenną ewolucję pękania zobrazowano stosując mikro-tomograf rentgenowski. Zdjęcia wykonano dla różnych cykli zmęczeniowych. Wyniki porównano z testami monotonicznymi. Jakościowa ewolucja objętości pękania ze wzrostem zmęczeniowego zniszczenia pokazała silnie nieliniowy kształt.

  • Frakcje azotu organicznego w wywarze gorzelnianym
    • Anna Wilińska
    • Krzysztof Czerwionka
    2019

    Wywar gorzelniany jest produktem ubocznym w procesie wytwarzania surowego spirytusu. W Polsce na jeden litr wyprodukowanego spirytusu powstaje od 9 do 14 litrów tego odpadu. Charakteryzuje się on wysokim ładunkiem ChZT oraz azotu ogólnego, występującego głównie w formie azotu organicznego. Przy wysokiej produkcji alkoholu stwarza to poważne problemy w zagospodarowaniu całej ilość powstającego wywaru. W pracy przedstawiono wyniki analiz składu pięciu wywarów gorzelnianych oraz odcieków powstających podczas ich odwirowania. Charakterystyka wywaru gorzelnianego oraz odcieków uzależniona była od składu oraz zawartości suchej masy wsadu wykorzystywanego w gorzelniach do produkcji alkoholu. W odciekach z odwirowania wywarów stwierdzono wysoki udział frakcji rozpuszczonej zawiązków organicznych (84 do 95% ChZT) oraz azotu organicznego (od 81 do 93% azotu ogólnego). W odniesieniu do frakcji azotu organicznego stwierdzono, że dla trzech z pięciu odcieków zdecydowanie dominowała frakcja rozpuszczona (DON), która stanowiła od 75 do 80% azotu organicznego. Natomiast dla dwóch pozostałych odcieków udział tej frakcji spadł do 40-50%, przy jednoczesnym wzroście udziału frakcji koloidalnej do 30-40%. Nie stwierdzono statystycznie istotnych zależności pomiędzy stężeniem frakcji DON i CON w odciekach, a innymi badanymi parametrami jakości odcieków lub wywarów.

  • Framework of an Evolutionary Multi-Objective Optimisation Method for Planning a Safe Trajectory for a Marine Autonomous Surface Ship
    • Rafał Szłapczyński
    • Mohammad Ghaemi
    2019 Full text Polish Maritime Research

    This paper represents the first stage of research into a multi-objective method of planning safe trajectories for marine autonomous surface ships (MASSs) involved in encounter situations. Our method applies an evolutionary multi-objective optimisation (EMO) approach to pursue three objectives: minimisation of the risk of collision, minimisation of fuel consumption due to collision avoidance manoeuvres, and minimisation of the extra time spent on collision avoidance manoeuvres. Until now, a fully multi-objective optimisation has not been applied to the real-time problem of planning safe trajectories; instead, this optimisation problem has usually been reduced to a single aggregated cost function covering all objectives. The aim is to develop a method of planning safe trajectories for MASSs that is able to simultaneously pursue the three abovementioned objectives, make decisions in real time and without interaction with a human operator, handle basic types of encounters (in open or restricted waters, and in good or restricted visibility) and guarantee compliance with the International Regulations for Preventing Collisions at Sea. It should also be mentioned that optimisation of the system based on each criterion may occur at the cost of the others, so a reasonable balance is applied here by means of a configurable trade-off. This is done throughout the EMO process by means of modified Pareto dominance rules and by using a multi-criteria decision-making phase to filter the output Pareto set and choose the final solution.

  • FROM HARVESTING TO DISTILLATION - EFFECT OF ANALYTICAL PROCEDURES ON THE YIELD AND CHEMICAL COMPOSITION OF RHODODENDRON TOMENTOSUM (LEDUM PALUSTRE) ESSENTIAL OIL
    • Anna Jesionek
    • Bożena Zabiegała
    • Adam Bucinski
    • Maria Łuczkiewicz
    2019 Full text Acta Poloniae Pharmaceutica - Drug Research

    Rhododendron tomentosum possesses the anti-inflammatory, analgesic and antimicrobial properties, determined by the chemical composition of its essential oil. The effects of place (Miszewko, Lubichowo) and time of harvesting (June, November) as well as drying (air-drying, oven-drying, freeze-drying) and isolation (in Deryng, Clevenger and Likens-Nickerson apparatus) procedures on the yield and quality of R. tomentosum essential oil were studied. Ledol (8.1-14.4%), palustrol (6.9-13.0%) and γ-terpineol (8.5-9.1%) predominated in the plants collected from Miszewko, while γ-terpineol (11.8-22.2%), p-cymene (5.3-12.6%) and geranyl acetate (5.7-7.5%) prevailed in the biomass from Lubichowo. The shoots produced more volatiles in the flowering phase than at the end of the vegetation. Oven-drying at 30OC with controlled air flow was suggested as the quick dehydration method. Hydrodistillation in Deryng and Clevenger apparatus resulted in comparatively high essential oil yield (about 1%). All studied drying and distillation methods did not influence significantly the general profile of R. tomentosum essential oil

  • From structure to luminescence investigation of oxyfluoride transparent glasses and glass-ceramics doped with Eu3+/Dy3+ ions
    • Michalina Walas
    • Marta Lisowska
    • Tomasz Lewandowski
    • Ana I. Becerro
    • Marcin Łapiński
    • Anna Synak
    • Wojciech Sadowski
    • Barbara Kościelska
    2019 JOURNAL OF ALLOYS AND COMPOUNDS

    Glasses and glass-ceramics with nominal composition 73 TeO2– 4BaO– 3Bi2O3–18SrF2-2RE2O3 (where RE = Eu, Dy) have been synthesized by conventional melt-quenching technique and subsequent heat treatment at 370 °C for 24 h in air atmosphere. Various Eu3+ to Dy3+ molar ratio have been applied to investigate luminescence properties in both glass and glass-ceramic matrices. Especially, white light emission through simultaneous excitation of Eu3+ and Dy3+ has been studied in detail. Influence of crystalline SrF2 phase on luminescence kinetics has been determined by luminescence decay time measurements. Presence of crystalline SrF2 phase has been confirmed by X-ray diffraction technique XRD and transmission electron microscopy TEM. X-ray photoelectron spectroscopy XPS and Fourier-transform infrared spectroscopy FTIR have been applied to get further insight into structural properties of glass and glass-ceramic materials. Color tunable white light emission has been obtained using UV excitation. Influence of the SrF2 crystallization on luminescence properties of prepared materials have been described in detail. Moreover, luminescence properties and especially emission color dependence on the Eu3+ to Dy3+ molar ratio have been exhaustively studied. Color-tunable white light emission has been observed as a result of simultaneous radiative transition of both, Eu3+ and Dy3+ ions when applying UV excitation. Judd – Ofelt and other optical parameters have been calculated based on luminescence emission spectra. Achieved results confirm that tellurite glass-ceramics containing SrF2 nanocrystals are good hosts for RE3+ ions and they can be considered as new phosphors for white light emitting diodes WLEDs.

  • Full scale CFD seakeeping simulations for case study ship redesigned from V-shaped bulbous bow to X-bow hull form
    • Karol Niklas
    • Hanna Pruszko
    2019 APPLIED OCEAN RESEARCH

    Increasing propulsion efficiency, safety, comfort and operability are of the great importance, especially for small ships operating on windy sites like the North Sea and the Baltic Sea. Seakeeping performance of ships and offshore structures can be analysed by different methods and the one that is becoming increasingly important is CFD RANS. The recent development of simulation techniques together with rising HPC accessibility enables performance of advanced seakeeping simulations for ships in a full scale. The paper presents CFD seakeeping analysis for a case study vessel in two variants: V-shaped bulbous bow hull form (as built) and innovative hull form (X-bow type). The study presents the influence of redesigning the ship on selected seakeeping aspects. The advanced CFD model, with the application of overset mesh technique, was described in detail. Selected numerical results were validated on the basis of experimental testing in a towing tank and showed good agreement. The approach demonstrated here of performing the CFD seakeeping simulations for the analysis of ship performance in a full scale and close to real loading conditions has direct application to the design process as well as in determination of optimal operational parameters of any ship.

  • Full-scale CFD simulations for the determination of ship resistance as a rational, alternative method to towing tank experiments
    • Karol Niklas
    • Hanna Pruszko
    2019 OCEAN ENGINEERING

    Results of ship resistance predictions obtained from towing tank experiments are affected by the method used to extrapolate from a model scale to a ship scale. Selection of method to determine a form factor is subjective and the extrapolation method is accurate for typical hull forms. For innovative hull forms the proper method for calculating the form factor is questionable. Moreover, the influence of the extrapolation method can be equally as important as the influence of a redesigned hull form itself. The paper presents novel numerical and experimental methods used to predict ship's total resistance in calm water. The results determined by towing tank experiments, full-scale CFD simulations and ship's sea trial measurements were compared. Depending on the method used, the determined form factor differed by 19%. As a result, the predicted calm water resistance varied from −6% to 11% relatively to sea trials data. For innovative hull forms in particular, full-scale CFD simulations should support the towing tank method. The results calculated by full-scale CFD varied from −10% to 4% relatively to sea trials data depending on the assumptions on hull roughness and turbulence model. The towing tank testing and full-scale CFD simulations can provide similar accuracy.

  • Fully Adaptive Savitzky-Golay Type Smoothers
    • Maciej Niedźwiecki
    • Marcin Ciołek
    2019 Full text

    The problem of adaptive signal smoothing is consid-ered and solved using the weighted basis function approach. Inthe special case of polynomial basis and uniform weighting theproposed method reduces down to the celebrated Savitzky-Golaysmoother. Data adaptiveness is achieved via parallel estimation.It is shown that for the polynomial and harmonic bases andcosinusoidal weighting sequences, the competing signal estimatescan be computed in both time-recursive and order-recursive way.

  • Functional safety and cyber security analysis for life cycle management of industrial control systems in hazardous plants and oil port critical infrastructure including insurance
    • Kazimierz Kosmowski
    • Dariusz Gołębiewski
    2019 Full text Journal of Polish Safety and Reliability Association, Summer Safety and Reliability Seminars

    This report addresses selected methodological aspects of proactive reliability, functional safety and cyber security management in life cycle of industrial automation and control systems (IACS) in hazardous plants and oil port critical installations based on the analysis of relevant hazards / threats and evaluation of related risks. In addition the insurance company point of view has been also considered, because nowadays the insurer, interested in decreasing risks to be insured, offers the expertise how to limit effectively risks in life cycle from the design conceptual stage of hazardous plant, through its reliable and safe operation, until decommissioning. Therefore, the risk evaluation model for insurance related decision making for the period considered, e.g. one year, should be plant specific with some predictive properties due to changing environment and business conditions, and usually considerable uncertainty involved. The objective is to evaluate and mitigate risks, and control them proactively, through undertaking appropriate activities within a process based management system according to elaborated policy and strategy that includes organisational and technical aspects, including preventive maintenance activities of sensitive equipment and updating in time the training programmes. Careful evaluating and controlling risks is also crucial for the insurance company. Basic activities of the risk engineers and underwriters in the insurance process are outlined in the context of identified hazards/threats and defined factors that significantly influence risks to be considered in evaluating the insurance premium in the context of terms and conditions specified.

  • Functionalized polyolefins, synthesis application and industrial relevance
    • Lidia Jasińska-Walc
    • Rob Duchateau
    • Miloud Bouyahyi
    2019

    Polymers play a key role in our modern life full of technical advances and a continuous request for new materials with tailored properties for a low price. Their excellent mechanical properties, good processability, chemical stability and low price make polyolefins the polymers of choice for most commodity and some more specialized applications. As a result, polyolefins account for over 65% of the total world demand of plastic materials. However, the major drawback of polyolefins is their lack of functionality, which results in low adhesion with other materials such as inorganic fillers, metals or other polymers. The availability of well-defined functionalized polyolefins will certainly increase the application window of polyolefins even more. Incorporation of polar functionalities into the polyolefins is believed to enhance the adhesive properties of the polymers and numerous reports describe the synthesis of such products either by reactive extrusion or by catalysis.[1] Yet, little is known about the actual properties of these materials and their potential applications. Many questions remain, like: Do functionalized polyolefins indeed show improved adhesion to polar substrates or improved paintability? What functionality level is required to obtain satisfying adhesive properties? How do these functionalities affect the polyolefin properties? Are there other applications for functionalized polyolefins than just improved adhesion? Over the last years, our group has evaluated the synthesis and material properties of functionalized polyolefins prepared by both catalysis and reactive extrusion and we have explored potential applications of such materials. This contribution will give a clear overview of the potential of functionalized polyolefins and the various challenges that have to be overcome to produce these products in a commercially viable manner. Issues like potential catalyst poisoning by functionalized comonomers and reactor fouling during in-reactor functionalization and differences in material properties of functionalized polyolefins obtained by reactive extrusion and in-reactor functionalization will be addressed. With some striking examples, it will be demonstrated that functionalized polyolefins can be used in applications usually reserved for specialty polymers.

  • Funkcja drenażowa geosyntetyków
    • Remigiusz Duszyński
    2019 Geoinżynieria, Drogi, Mosty, Tunele

    Spośród wielu funkcji geosyntetyków, które powszechnie znajdują zastosowanie w budownictwie jedną z istotniejszych jest funkcja drenażowa. Zapewnienie długotrwałego, niezawodnego funkcjonowania drenażu wymaga przyjęcia odpowiedniego geokompozytu drenażowego. To złożone zagadnienie zostało przedstawione w poniższym artykule.

  • FUNKCJONALIZOWANE ADSORBENTY WĘGLOWE DO EFEKTYWNEGO USUWANIA JONÓW METALI Z WODY
    • Małgorzata Nadolska
    • Kamila Sadowska
    2019 Full text

    W niniejszej pracy zbadano skuteczność adsorpcyjnego usuwania jonów Hg2+, Sr2+ z roztworów wodnych, z wykorzystaniem funkcjonalizowanych materiałów węglowych. Jako adsorbenty zastosowano nanorurki węglowe, tlenek grafenu oraz węgiel aktywny. Oprócz często stosowanej praktyki jaką jest wykorzystanie materiałów węglowych które na swojej powierzchni zawierają tlenowe grupy funkcyjne, zaproponowano aby na powierzchnię materiałów węglowych wprowadzić dodatkowe grupy funkcyjne w postaci grup fosfonowych. W celu określenia rodzaju powierzchniowych grup funkcyjnych oraz oszacowanie ich ilości (a następnie określenia ich wpływu na zdolności adsorpcyjne jonów Hg2+, Sr2+), materiały scharakteryzowano za pomocą metod spektroskopowych (FTIR, Raman), TGA oraz SEM.

  • Further development of the poroelastic road surface within the new Polish project SEPOR
    • Piotr Mioduszewski
    • Jerzy Ejsmont
    • Grzegorz Ronowski
    • Stanisław Taryma
    2019

    Road surfaces have a direct impact on noise generated by rolling tyres, the main and dominant source of noise of moving vehicles. Road surface texture, porosity and stiffness/elasticity govern the pavement contribution to tyre/road noise the most. An experimental PoroElastic Road Surface (PERS) is a wearing course with a high content of interconnected voids (pores) and with an elastic behavior due to the use of small particles of rubber as the main aggregate. It was already proved, that using that type of pavement, a road traffic noise reduction up to 12 dB can be achieved. The new project SEPOR founded by the Polish National Centre for Research and Development has started in 2018 aiming in further development of poroelastic road surface. Its main goal is to enhance durability of PERS by optimization of mix composition, improvement of the production process, increasing the interlayer bonding strength and to optimize noise reduction and skid resistance. Experimental test sections will be constructed within a trafficked road and tested for noise, rolling resistance, skid resistance and fire suppression properties. The paper presents the results of noise and rolling resistance measurements performed on a pilot small-scale test section of PERS built on a construction yard.

  • Galvanostatic impedance measurements for the efficient adsorption isotherm construction in corrosion inhibitor studies
    • Jacek Ryl
    • Joanna Wysocka
    • Mateusz Cieślik
    • Stefan Krakowiak
    • Paweł Ślepski
    2019

    We present an approach towards an accurate and time-efficient adsorption isotherm determination to evaluate the corrosion inhibitor interaction in electrolytic environments. The approach is based on dynamic impedance spectroscopy measurements in galvanostatic mode (g-DEIS). The studied corrosion inhibitor is continuously injected between the secondary cell and the corrosion cell. The efficiency corresponding to instantaneous inhibitor concentration is determined based on the charge transfer resistance. The galvanostatic mode ensures lack of artificial polarization component resulting from alteration of the corrosion potential by studied inhibitor. Analysis of the double-layer capacitance course of changes delivers information on the inhibitor concentration sufficient to form monolayer of the inhibitor, representing boundary conditions for Langmuir adsorption model validity. Its utility was confirmed using ellipsometry while the g-DEIS studies were cross-verified by other electrochemical tools (potentiodynamic polarization, EIS) as well as XPS and microscopic analyses. The discussed approach was first used to investigate the corrosion inhibition efficiency of various carboxylic acids towards aluminium alloys in alkaline environments, although more recently it was tested to evaluate the efficiency of complex inhibitor extracts, such as bee pollen inhibition efficiency.

  • Gas Turbine Cycle with External Combustion Chamber for Prosumer and Distributed Energy Systems
    • Dariusz Mikielewicz
    • Krzysztof Kosowski
    • Karol Tucki
    • Marian Piwowarski
    • Robert Stępień
    • Olga Orynycz
    • Wojciech Włodarski
    2019 Full text ENERGIES

    The use of various biofuels, usually of relatively small Lower Heating Value (LHV), affects the gas turbine efficiency. The present paper shows that applying the proposed air by-pass system of the combustor at the turbine exit causes tan increase of efficiency of the turbine cycle increased by a few points. This solution appears very promising also in combined gas/steam turbine power plants. The comparison of a turbine set operating according to an open cycle with partial bypassing of external combustion chamber at the turbine exit (a new solution) and, for comparison, a turbine set operating according to an open cycle with a regenerator. The calculations were carried out for different fuels: gas from biomass gasification (LHV = 4.4 MJ/kg), biogas (LHV = 17.5 MJ/kg) and methane (LHV = 50 MJ/kg). It is demonstrated that analyzed solution enables construction of several kW power microturbines that might be used on a local scale. Such turbines, operated by prosumer’s type of organizations may change the efficiency of electricity generation on a country-wide scale evidently contributing to the sustainability of power generation, as well as the economy as a whole.

  • Gas‐Phase Removal of Indoor Volatile Organic Compounds and Airborne Microorganisms Over Mono‐ and Bimetal‐Modified (Pt, Cu, Ag) Titanium(IV) Oxide Nanocomposites
    • Izabela Wysocka
    • A. Markowska-Szczupak
    • Piotr Szweda
    • Jacek Ryl
    • Maya Endo-Kimura
    • Kowalska Ewa
    • Grzegorz Nowaczyk
    • Anna Zielińska-Jurek
    • Agata Markowska-Szczupak
    2019 INDOOR AIR

    The photocatalytic deactivation of volatile organic compounds and mold fungi using TiO2 modified with mono‐ and bimetallic (Pt, Cu, Ag) particles is reported in this study. The mono‐ and bimetal‐modified (Pt, Cu, Ag) titanium(IV) oxide photocatalysts were prepared by chemical reduction method and characterized using XRD, XPS, DR/UV‐Vis, BET and TEM analysis. The effect of incident light, type and content of mono‐ and bimetallic nanoparticles deposited on titanium(IV) oxide was studied. Photocatalytic activity of as‐prepared nanocomposites was examined in the gas phase using LEDs array. High photocatalytic activity of Ag/Pt‐TiO2 and Cu/Pt‐TiO2 in the reaction of toluene degradation resulted from improved efficiency of interfacial charge transfer process, which was consistent with the fluorescence quenching effect revealed by photoluminescence (PL) emission spectra. The photocatalytic deactivation of Penicillium chrysogenum, a pathogenic fungi present in the indoor environment, especially in a damp or water‐damaged building using mono‐ and bimetal‐modified (Pt, Cu, Ag) titanium(IV) oxide was evaluated for the first time. TiO2 modified with mono‐ and bimetallic NPs of Ag/Pt, Cu and Ag deposited on TiO2 exhibited improved fungicidal activity under LEDs illumination than pure TiO2.

  • Gate Driver with Overcurrent Protection Circuit for GaN Transistors
    • Paweł Derkacz
    • Piotr Musznicki
    2019 Full text Przegląd Elektrotechniczny

    The improvement of the gate driver for GaN transistor is presented in this paper. The proposed topology contains the overcurrent protectionwith the two-stage turning off and independent control of turn on and off time of the GaN transistor. The operation of driver and its application in thehalf-bridge converter are described using both simulation and prototype measurements. The overcurrent protection was tested in Double Pulse Test(DPT) conditions.