Repozytorium publikacji - Politechnika Gdańska

Ustawienia strony

english
Repozytorium publikacji
Politechniki Gdańskiej

Pokaż publikacje z roku

Ostatnie pozycje

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  • COVID-19 and digital deprivation in Poland
    • Marta Kuc-Czarnecka
    2020 Pełny tekst Oeconomia Copernicana

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  • Data Acquisition and Processing for GeoAI Models to Support Sustainable Agricultural Practices
    • Agustin Garcia Pereira
    • Adegboyega Ojo
    • Curry Edward
    • Lukasz Porwol
    2020 Pełny tekst

    There are growing opportunities to leverage new technologies and data sources to address global problems related to sustainability, climate change, and biodiversity loss. The emerging discipline of GeoAI resulting from the convergence of AI and Geospatial science (Geo-AI) is enabling the possibility to harness the increasingly available open Earth Observation data collected from different constellations of satellites and sensors with high spatial, spectral and temporal resolutions. However, transforming these raw data into high-quality datasets that could be used for training AI and specifically deep learning models are technically challenging. This paper describes the process and results of synthesizing labelled-datasets that could be used for training AI (specifically Convolutional Neural Networks) models for determining agricultural land use pattern to support decisions for sustainable farming. In our opinion, this work is a significant step forward in addressing the paucity of usable datasets for developing scalable GeoAI models for sustainable agriculture.

  • Data governance: Organizing data for trustworthy Artificial Intelligence
    • Marijn Janssen
    • Paul Brous
    • Elsa Estevez
    • Luis S. Barbosa
    • Tomasz Janowski
    2020 Pełny tekst GOVERNMENT INFORMATION QUARTERLY

    The rise of Big, Open and Linked Data (BOLD) enables Big Data Algorithmic Systems (BDAS) which are often based on machine learning, neural networks and other forms of Artificial Intelligence (AI). As such systems are increasingly requested to make decisions that are consequential to individuals, communities and society at large, their failures cannot be tolerated, and they are subject to stringent regulatory and ethical requirements. However, they all rely on data which is not only big, open and linked but varied, dynamic and streamed at high speeds in real-time. Managing such data is challenging. To overcome such challenges and utilize opportunities for BDAS, organizations are increasingly developing advanced data governance capabilities. This paper reviews challenges and approaches to data governance for such systems, and proposes a framework for data governance for trustworthy BDAS. The framework promotes the stewardship of data, processes and algorithms, the controlled opening of data and algorithms to enable external scrutiny, trusted information sharing within and between organizations, risk-based governance, system-level controls, and data control through shared ownership and self-sovereign identities. The framework is based on 13 design principles and is proposed incrementally, for a single organization and multiple networked organizations.

  • Data regarding a new, vector-enzymatic DNA fragment amplification-expression technology for the construction of artificial, concatemeric DNA, RNA and proteins, as well as biological effects of selected polypeptides obtained using this method
    • Piotr Skowron
    • Natalia Krawczun
    • Joanna Żebrowska
    • Daria Krefft
    • Olga Żołnierkiewicz
    • Marta Bielawa
    • Joanna Jeżewska-Frąckowiak
    • Łukasz Janus
    • Małgorzata Witkowska
    • Małgorzata Palczewska
    • Adriana Schumacher
    • Anna Wardowska
    • Milena Deptuła
    • Artur Czupryn
    • Piotr Mucha
    • Arkadiusz Piotrowski
    • Paweł Sachadyn
    • Sylwia Rodziewicz-Motowidło
    • Michal Pikuła
    • Agnieszka Zylicz-Stachula
    2020 Pełny tekst Data in Brief

    Applications of bioactive peptides and polypeptides are emerging in areas such as drug development and drug delivery systems. These compounds are bioactive, biocompatible and represent a wide range of chemical properties, enabling further adjustments of obtained biomaterials. However, delivering large quantities of peptide derivatives is still challenging. Several methods have been developed for the production of concatemers – multiple copies of the desired protein segments. We have presented an efficient method for the production of peptides of desired length, expressed from concatemeric Open Reading Frame. The method employs specific amplification-expression DNA vectors. The main methodological approaches are described by Skowron et al., 2020 [1]. As an illustration of the demonstrated method's utility, an epitope from the S protein of Hepatitis B virus (HBV) was amplified. Additionally, peptides, showing potentially pro-regenerative properties, derived from the angiopoietin-related growth factor (AGF) were designed and amplified. Here we present a dataset including: (i) detailed protocols for the purification of HBV and AGF – derived polyepitopic protein concatemers, (ii) sequences of the designed primers, vectors and recombinant constructs (iii) data on cytotoxicity, immunogenicity and stability of AGF-derived polypeptides.

  • Daylight Appraisal Classes For Achitecture Students A Survey Combined With A Practical Assessment For Educational Training Recommendations
    • Natalia Sokół
    • Marta Waczyńska
    • Justyna Martyniuk-Pęczek
    2020 Pełny tekst

    The main objectives of this article are: (i) to present the relations between architecture students' subjective assessment of daylight in classrooms and the objective evaluation of daylit conditions using daylight simulations tools, (ii) to formulate guidelines and recommendations on daylight appraisal methods and tools which may be useful in architectural training. The methodology used includes an evaluation of the results of the direct questionnaire and the computational simulations of the observed conditions. One hundred ninety-four architecture students form three different universities in Poland assessed daylight in 13 different classrooms. The questionnaire aimed to investigate relationships between daylight subjective assessment, students’ perception and daylight knowledge. This paper focuses only on the results of the subjective appraisal of daylit interior spaces and the objective evaluation of the investigated conditions. The simulations of Daylight Factor and Daylight Autonomy were carried out using various available software and the available climate and weather data (for DA). The key findings of the study are: Daylight appraisal part: (i) Daylight factor simulations results correspond with subjective students' assessments of daylight sufficiency within the rooms for eight out of 13 cases. (ii) The were no significant correlations found between the mean illuminances values and the subjective students' appraisals of daylight. The subjective description of daylight within the investigated classrooms was similar (medium) for all the sessions. (iii) The subjective perception of uniformity for task illumination was rated by observers as a medium, while the mean illuminance levels varied from 61 to 460 lx. Architectural training part: (iv) The use of advanced computer daylight simulations tools supports educational activities and aids architectural design, only if the students can comprehend the obtained results (v) Available informative packages should cover contemporary analysis daylight tools.

  • Debonding Size Estimation in Reinforced Concrete Beams Using Guided Wave-Based Method
    • Beata Zima
    • Rafał Kędra
    2020 Pełny tekst SENSORS

    The following paper presents the results of the theoretical and experimental analysis of the influence of debonding size on guided wave propagation in reinforced concrete beams. The main aim of the paper is a development of a novel, baseline-free method for determining the total area of debonding between steel rebar embedded in a concrete cover on the basis of the average wave velocity or the time of flight. The correctness of the developed relationships was verified during the experimental tests, which included propagation of guided waves in concrete beams with the varying debonding size, shape and location. The analysis of the collected results proved that guided waves can be efficiently used not only in the debonding detection, but also in an exact determining of its total area, which is extremely important in the context of the nondestructive assessment of the load capacity of the reinforced concrete structures. The undeniable advantage of the proposed method is that there are no requirements for any baseline signals collected for an undamaged structure. The paper comprises of the detailed step by step algorithm description and a discussion of both the advantages and disadvantages.

  • Decomposition of halogenated nucleobases by surface plasmon resonance excitation of gold nanoparticles
    • Telma S. Marques
    • Małgorzata Śmiałek-Telega
    • Robin Schürmann
    • Ilko Bald
    • Maria Raposo
    • Samuel Eden
    • Nigel J. Mason
    2020 Pełny tekst EUROPEAN PHYSICAL JOURNAL D

    Halogenated uracil derivatives are of great interest in modern cancer therapy, either as chemotherapeutics or radiosensitisers depending on their halogen atom. This work applies UV-Vis spectroscopy to study the radiation damage of uracil, 5-bromouracil and 5- uorouracil dissolved in water in the presence of gold nanoparticles upon irradiation with an Nd:YAG ns-pulsed laser operating at 532nm at dierent uences. Gold nanoparticles absorb light eciently by their surface plasmon resonance and can signicantly damage DNA in their vicinity by an increase of temperature and the generation of reactive secondary species, notably radical fragments and low energy electrons. A recent study using the same experimental approach characterized the ecient laser-induced decomposition of the pyrimidine ring structure of 5-bromouracil mediated by the surface plasmon resonance of gold nanoparticles. The present results show that the presence of irradiated gold nanoparticles decomposes the ring structure of uracil and its halogenated derivatives with similar eciency. In addition to the fragmentation of the pyrimidine ring, for 5-bromouracil the cleavage of the carbon-halogen bond could be observed, whereas for 5- uorouracil this reaction channel was inhibited. Locally-released halogen atoms can react with molecular groups within DNA, hence this result indicates a specic mechanism by which doping with 5-bromouracil can enhance DNA damage in the proximity of laser irradiated gold nanoparticles.

  • Decrease in Photovoltaic Module Efficiency Due to Deposition of Pollutants
    • Ewa Klugmann-Radziemska
    • Małgorzata Rudnicka
    2020 Pełny tekst IEEE Journal of Photovoltaics

    The deposition of pollutants on the surface of photovoltaic (PV) modules reduce the efficiency that can be achieved in given climatic conditions. This results in the loss of energy yield obtained from the solar installation. A number of factors determine the scale of this problem. The first of these is the amount of impurities deposited, the associated amount of precipitation, and the speed and direction of the wind. A second aspect is the type of pollution and the composition and structure of the sludge, which depends on the location of the installation. The type of installation, either stationary or sun tracking, is essential because the angle of inclination of modules, depending on the latitude, will determine the amount of dust deposited, especially for stationary installations. The observed decrease in efficiency of PV modules covered with dust equals 6–10% of the efficiency of a module free of impurities. This means that the user should maintain the module surface and schedule routine cleaning.

  • Decyzje optymalne z Solverem
    • Anna Baj-Rogowska
    2020

    Na rynku można odnaleźć wiele podręczników pomocnych w rozwijaniu kompetencji związanych z posługiwaniem się arkuszem kalkulacyjnym w praktyce menedżerskiej. Niewiele jest natomiast pozycji literaturowych pokazujących możliwości wykorzystania MS Solver do wspomagania decyzji. Niniejsza książka ma za zadanie wypełnić tę lukę. Jej celem jest przedstawienie możliwości dodatku Solver w procesie podejmowania decyzji optymalnych. Intencją Autorki było stworzenie podręcznika dla osób zainteresowanych samodzielną nauką pracy z MS Excel Solver. Niniejsze opracowanie składa się z trzech rozdziałów. Rozdział pierwszy zawiera teoretyczne podstawy wprowadzające do zagadnień podejmowania decyzji optymalnych. Przedstawiono w nim podstawowe pojęcia z tego zakresu, omówiono czym jest proces rozwiązywania problemów decyzyjnych ze szczególnym rozróżnieniem pomiędzy rozwiązywaniem problemów decyzyjnych a ich podejmowaniem. Drugi rozdział został dedykowany przedstawieniu funkcjonalności dodatku Solver wraz z omówieniem opcji ustawień i metod rozwiązań dostępnych w programie oraz raportów wyników, wrażliwości i granic. Na tak przygotowanej podbudowie teoretycznej w dalszej części rozdziału zaprezentowano praktyczne rozwiązanie krok po kroku prostego zadania decyzyjnego. Takie podejście przygotowuje Czytelnika do treści zawartych w rozdziale trzecim. Przedstawiono tutaj różnorodne i znacznie bardziej złożone problemy decyzyjne. Dobór przykładów ma na celu pokazanie potencjału Solvera.

  • Deep eutectic solvents vs ionic liquids: Similarities and differences
    • Justyna Płotka-Wasylka
    • Miguel De la Guardia
    • Vasil Andruch
    • Mária Vilková
    2020 Pełny tekst MICROCHEMICAL JOURNAL

    Deep eutectic solvents (DES) were introduced as an alternative to ionic liquids (IL) to overcome the drawbacks of IL solvents. However, some authors consider them to be a subclass of ILs. In contrast, other authors emphasize that these are by their nature independent, different groups of substances. Thus, the question arises: Which solvent group should DESs belong to? Maybe a new class should be added to the existing ones. The aim of this work is to attract the attention of researchers using DES in their studies to the need for a proper use of terms.

  • Deep Instance Segmentation of Laboratory Animals in Thermal Images
    • Magdalena Mazur-Milecka
    • Tomasz Kocejko
    • Jacek Rumiński
    2020 Pełny tekst Applied Sciences-Basel

    In this paper we focus on the role of deep instance segmentation of laboratory rodents in thermal images. Thermal imaging is very suitable to observe the behaviour of laboratory animals, especially in low light conditions. It is an non-intrusive method allowing to monitor the activity of animals and potentially observe some physiological changes expressed in dynamic thermal patterns. The analysis of the recorded sequence of thermal images requires smart algorithms for automatic processing of millions of thermal frames. Instance image segmentation allows to extract each animal from a frame and track its activity and thermal patterns. In this work, we adopted two instance segmentation algorithms, i.e., Mask R-CNN and TensorMask. Both methods in different configurations were applied to a set of thermal sequences, and both achieved high results. The best results were obtained for the TensorMask model, initially pre-trained on visible light images and finally trained on thermal images of rodents. The achieved mean average precision was above 90 percent, which proves that model pre-training on visible images can improve results of thermal image segmentation.

  • Deep learning based thermal image segmentation for laboratory animals tracking
    • Magdalena Mazur-Milecka
    • Jacek Rumiński
    2020 QIRT Journal

    Automated systems for behaviour classification of laboratory animals are an attractive alternative to manual scoring. However, the proper animals separation and tracking, especially when they are in close contact, is the bottleneck of the behaviour analysis systems. In this paper, we propose a method for the segmentation of thermal images of laboratory rats that are in close contact during social behaviour tests. For this, we are using thermal imaging – a technology that requires neither light nor human presence. The aim of the study was: (1) an efficiency analysis of deep learning based image segmentation algorithms for the need of laboratory rats images, (2) analysis of different methods of original thermal data conversion to grey scale images for the purpose of the segmentation, (3) evaluation of the image data range impact on segmentation results using deep learning networks. We have trained U-Net and V-Net architectures with images obtained from different temperature ranges. The results indicate, that networks trained on images containing a narrow range of temperature data equal to animals’ body temperature or even its part, are able to better perform the object segmentation than networks trained on the original data.

  • Deep learning for recommending subscription-limited documents
    • Grzegorz Chłodziński
    • Karol Woźniak
    2020 Pełny tekst

    Documents recommendation for a commercial, subscription-based online platform is important due to the difficulty in navigation through a large volume and diversity of content available to clients. However, this is also a challenging task due to the number of new documents added every day and decreasing relevance of older contents. To solve this problem, we propose deep neural network architecture that combines autoencoder with multilayer perceptron in a hybrid recommender system. We train our model using real-world historical data from commercial platform using interactions to capture user similarity and categorical document features to predict the probability of a user-document interaction. Our experimental results demonstrate the effectiveness of the proposed architecture. We plan to release our model in a commercial online platform to support a personalized user experience.

  • Deep Learning-Based Intrusion System for Vehicular Ad Hoc Networks
    • Li Fei
    • Zhang Jiayan
    • Song Jiaqi
    • Edward Szczerbicki
    2020 Pełny tekst CMC-Computers Materials & Continua

    The increasing use of the Internet with vehicles has made travel more convenient. However, hackers can attack intelligent vehicles through various technical loopholes, resulting in a range of security issues. Due to these security issues, the safety protection technology of the in-vehicle system has become a focus of research. Using the advanced autoencoder network and recurrent neural network in deep learning, we investigated the intrusion detection system based on the in-vehicle system. We combined two algorithms to realize the efficient learning of the vehicle’s boundary behavior and the detection of intrusive behavior. In order to verify the accuracy and efficiency of the proposed model, it was evaluated using real vehicle data. The experimental results show that the combination of the two technologies can effectively and accurately identify abnormal boundary behavior. The parameters of the model are self-iteratively updated using the time-based back propagation algorithm. We verified that the model proposed in this study can reach a nearly 96% accurate detection rate.

  • Defective TiO2 Core-Shell Magnetic Photocatalyst Modified with Plasmonic Nanoparticles for Visible Light-Induced Photocatalytic Activity
    • Zuzanna Bielan
    • Agnieszka Sulowska
    • Szymon Dudziak
    • Siuzdak Katarzyna
    • Jacek Ryl
    • Anna Zielińska-Jurek
    2020 Pełny tekst Catalysts

    In the presented work, for the first time, the metal-modified defective titanium(IV) oxide nanoparticles with well-defined titanium vacancies, was successfully obtained. Introducing platinum and copper nanoparticles (NPs) as surface modifiers of defective d-TiO2 significantly increased the photocatalytic activity in both UV-Vis and Vis light ranges. Moreover, metal NPs deposition on the magnetic core allowed for the effective separation and reuse of the nanometer-sized photocatalyst from the suspension after the treatment process. The obtained Fe3O4@SiO2/d-TiO2-Pt/Cu photocatalysts were characterized by X-ray diffractometry (XRD) and specific surface area (BET) measurements, UV-Vis diffuse reflectance spectroscopy (DR-UV/Vis), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Further, the mechanism of phenol degradation and the role of four oxidative species (h+, e−, •OH, and •O2−) in the studied photocatalytic process were investigated

  • Deflated Preconditioned Solvers for Parametrized Local Model Order Reduction
    • Martyna Mul
    • Michał Mrozowski
    2020

    One of steps in the design of microwave filters is numerical tuning using full-wave simulators. Typically, it is a time-consuming process as it uses advanced computational methods, e.g. the finite-element method (FEM) and it usually requires multiple optimization steps before the specification goals are met. FEM involves solving a large sparse system of equations at many frequency points and therefore its computational cost is high. One of the ideas to speed up the numerical optimization is parametrized model-order reduction (PMOR). The key point in model order reduction, is that the original large sparse system of FE equations is replaced with a small and dense one, that can be solved at many frequency points with substantially smaller computational effort. PMOR yields in the parameter dependent reduced-order model which might be reused in subsequent optimization steps.

  • Deformation and Surface Color Changes of Beech and Oak Wood Lamellas Resulting from the Drying Process
    • Jacek Barański
    • Aleksandra Konopka
    • Tatiana Vilkovská
    • Ivan Klement
    • Peter Vilkovský
    2020 Pełny tekst BIORESOURCES

    The drying process was examined relative to parameters’ influence on the deformation and surface layer color changes of beech wood (Fagus sylvatica L.) and oak wood (Quercus robur L.). The goal was to analyze the impact of drying process conditions, wood and growth rings types, and load on the deformation and surface color changes of drying thin wooden elements. A further aim was to reduce the time of the lamella drying and minimize wood products defects. During each drying, 40 pieces of wood were dried, divided into two groups. For the first group, 30 pieces were dried under a uniformly distributed load of approximately 50 kg, while for the second group, 10 samples were dried without weight. The lamellas dried under load exhibited fewer cup, bow, and twist deformations than the lamellas dried without load. Cracks in the dried lamellas occurred comparably in those dried under and without load. Color changes in the specimens before and after drying were observed and measured. The differences in colorimetric parameters (a, b, and L) between wood without defects and with defects were less marked after drying than before drying. The color changes were only noticed in the surface layers of the specimens.

  • Degradation of ferritic X10CrAlSi18 stainless steel caused by slurry
    • Alicja Krella
    • Marta Buszko
    • Grzegorz Gajowiec
    2020 ENGINEERING FAILURE ANALYSIS

    The slurry erosion tests of ferritic X10CrAlSi18 steel were carried out using a slurry pot device. In order to investigate the erosion process, two series of tests were performed: first one with a constant impact velocity of 5 m/s, 7 m/s and 9 m/s and the second one, during which the impact velocity was changed after every exposure. During each test, an influence of test conditions on volume loss, surface hardness and roughness with exposure time was studied. The normalized erosion rate and erosion efficiency parameter increased linearly with velocity in the range between 5 and 9 m/s. Surface hardness increased exponentially with an exponent n = 0.27. The erosive efficiency parameter determined for tests carried out with variable impact velocity was higher than for tests with constant velocity. The erosion performance increased as the difference in consecutive impact velocity increased. At the beginning of slurry tests, surface hardness and roughness increased rapidly. A fluctuation in erosion rate and surface roughness was noted in the tests performed with variable impact velocity. The amplitudes of these fluctuations decreased with the test duration. Surface hardness influenced damage formed on the specimen’s surface. With increasing surface hardness, surface roughness (Ra parameter) decreased. For surface hardness over 280 HV flakes were formed on the specimen surface.

  • Degradation of Kinematic PPP of GNSS Stations in Central Europe Caused by Medium-Scale Traveling Ionospheric Disturbances During the St. Patrick’s Day 2015 Geomagnetic Storm
    • Mateusz Poniatowski
    • Grzegorz Nykiel
    2020 Pełny tekst Remote Sensing

    In solar cycle 24, the strongest geomagnetic storm took place on March 17, 2015, when the geomagnetic activity index was as high as -223 nT. To verify the impact that the storm had on the Global Navigation Satellite System (GNSS)’s positioning accuracy and precision, we used 30-s observations from 15 reference stations located in Central Europe. For each of them, we applied kinematic precise point positioning (PPP) using gLAB software for the day of the storm and, for comparison, for a selected quiet day (13 March 2015). Based on the conducted analyses, we found out that the position root mean square (RMS) values on the day of the geomagnetic storm were significantly high and amounted to several dozen centimeters. The average RMS for the altitude coordinates was 0.58 m between 12:00 and 24:00 (GPS time), and 0.37 and 0.26 m for directions North and East, respectively. The compromised accuracy level was caused by a sudden decrease in the number of satellites used for calculations. This was due to a high number of cycle slips (CSs) detected during this period. The occurrence of these effects was strictly correlated with the appearance of traveling ionospheric disturbances (TIDs). This was proven by analyzing changes in the total electron content (TEC) estimated for each station–satellite pair.

  • Degree of monopoly and market power vs. price flexibility in Polish economy: empirical analysis based on COICOP classification
    • Paweł Umiński
    2020 Pełny tekst Oeconomia Copernicana

    Research background: The issue of price flexibility is crucial in the economy both in the aspect of company theory and its macroeconomic consequences. In a number of publications, the sources of variable price flexibility are linked to the market power of enterprises as well as the market structure that has developed in a given branch. It is difficult to indicate empirical studies that would state clearly whether price flexibility depends on the degree of monopoly or the market power of enterprises. This paper concerns that particular field of study. Purpose of the article: The purpose of the paper is to present the statistical dependence of the degree of monopoly and market power vs. price flexibility in the economy. Methods: The analysis has been conducted using aggregated data concerning Polish economy in the period from 2001 to 2013, based on COICOP. The degree of monopoly indicator was the average number of companies in a given branch, following the classical models of market structures; the market power indicator was the average net revenue from sales of products per enterprise representing a given branch; the measure of price flexibility was the probability of price variation estimated using the Calvo pricing model. It is, therefore, a frequency-based approach to price flexibility. Statistical dependence was analyzed using the Spearman's rank and Kendall’s tau correlation coefficient and simple regression models. Findings & Value added: The outcomes indicate that in the case of Poland in the analyzed period there is no statistically significant relation between the degree of monopoly and price flexibility and also between the market power and price flexibility. Thus, the findings of the analysis support the studies which reject the assumption that higher degree of monopoly or higher market power of an enterprise is followed by less flexible prices.

  • Density functional LCAO calculations of vibrational modes and phonon density of states in the strained single-layer phosphorene
    • Krzysztof Pyrchla
    • Robert Bogdanowicz
    2020 Pełny tekst APPLIED SURFACE SCIENCE

    The paper presents an investigation of phosphorene under axial strain on the phonon density of states and vibrational modes. The studies were performed by means of density functional theory (DFT) within the linear combination of atomic orbitals (LCAO). The strained models were constructed using optimised supercell techniques. The vibrational mode spectra were estimated for strains applied for both the zigzag and armchair directions of phosphorene. This approach is an attractive candidate for the calculation the dynamical matrix of the system because its numerical complexity gradually increases together with the size of the analysed cell. The shift of peaks in the PDOS of black phosphorene is monotonic, and inversely proportional to the applied strain over the zigzag direction. This relation is valid for small strains (below 10%) of peaks corresponding to modes B2g and Ag2. For a strain applied over the armchair PDOS, the shifts are proportional to the strain. The peak shifts tend to become higher as the strain increases. This dependence is not monotonic, and is clearly more rapid for compressing strains. Moreover, the peaks shift slower for an armchair strain than for a zigzag strain, revealing its strong anisotropy.

  • Deodorization of model biogas by means of novel non-ionic deep eutectic solvent
    • Edyta Słupek
    • Patrycja Makoś
    • Jacek Gębicki
    2020 Pełny tekst Archives of Environmental Protection

    The paper presents new non-ionic deep eutectic solvent (DES) composed of natural and non-toxic components i.e. guaiacol, camphor and levulinic acid in 1:1:3 molar ratio as a promising absorbent for removal of selected volatile organic compounds (VOCs) including dichloromethane, toluene, hexamethyldisiloxane and propionaldehyde from model biogas. The affi nity of DES for VOCs was determined as vapour-liquid coeffi cients and the results were compared with several well-known DESs based on quaternary ammonium salt as well as n-hexadecane and water. For new DES, the absorption process was carried out under dynamic conditions. The results indicate that non-ionic DES has high affi nity and capacity for VOCs being comparable to n-hexadecane. In addition, absorbed VOCs could be easily desorbed from DES using activated carbon and absorbent could be re-use minimum five times without signifi cant loss of absorption capacity

  • DESIGN ANALYSIS OF HYBRID GAS TURBINE - FUEL CELL POWER PLANT IN STATIONARY AND MARINE APPLICATIONS
    • Tomasz Kwaśniewski
    • Marian Piwowarski
    2020 Pełny tekst Polish Maritime Research

    The paper concerns design analysis of a hybrid gas turbine power plant with a fuel cell (stack). The aim of this work was to find the most favorable variant of the medium capacity (approximately 50 MW) hybrid system. In the article, computational analysis of two variants of such a system was carried out. The analysis let to calculate capacity, efficiency of both variants and other parameters like flu gas temperature. The paper presents that such a hybrid cycles can theoretically achieve extremely high efficiency over 60%. The most favorable one was selected for further detailed thermodynamic and flow calculations. As part of this calculation, a multi-stage axial compressor, axial turbine, fuel cell (stack) and regenerative heat exchanger were designed. Then an analysis of the profitability of the installation was carried out, which showed that the current state of development of this technology and its prices make the project unprofitable. For several years, however, tendencies of decreasing prices of fuel cells have been observed, which allows to conclude that hybrid systems will start to be created. This may apply to both stationary and marine applications. Hybrid solutions related to electrical power transmission, including fuel cells, are real and very promising for smaller car ferries and shorter ferry routes.

  • Design Analysis of Micro Gas Turbines in Closed Cycles
    • Krzysztof Kosowski
    • Marian Piwowarski
    2020 Pełny tekst ENERGIES

    The problems faced by designers of micro-turbines are connected with a very small volume flow rate of working media which leads to small blades’ height and high rotor speed. In the case of gas turbines this limitation can be overcome by the application of a closed cycle with very low pressure at the compressor inlet (lower than atmospheric pressure). In this way we may apply a micro gas turbine unit of accepted efficiency to work in a similar range of temperatures and the same pressure ratios, but in the range of smaller pressure values and smaller mass flow rate. Thus, we can obtain a gas turbine of a very small output but of the efficiency typical of gas turbines with a much higher power. In the paper the results of the thermodynamic calculations of the turbine cycles are discussed and the designed gas turbine flow parts are presented. Suggestions of the design solutions of micro gas turbines for different values of power output are proposed. This new approach to gas turbine arrangement makes it possible to build a gas turbine unit of a very small output and a high efficiency. The calculations of cycle and gas turbine design were performed for different cycle parameters and different working media (air, nitrogen, hydrogen, helium, xenon and carbon dioxide).

  • Design and characterization of apatite La9.8Si5.7Mg0.3O26±δ-based micro-tubular solid oxide fuel cells
    • Sea-Fue Wang
    • Yung-Fu Hsu
    • Pu Hsia
    • Wei-Kai Hung
    • Piotr Jasiński
    2020 JOURNAL OF POWER SOURCES

    In this study, electrolyte-supported (Cell A) and anode-supported (Cell B) micro-tubular solid oxide fuel cells (SOFCs) based on the La9.8Si5.7Mg0.3O26±δ (LSMO) electrolyte is built through an extrusion and dip-coating processes. The formulations and process conditions for these cells are established and optimized. Both cell configurations show no visible delamination or cracking, and reaction zones and inter-diffusion of any species are absent at the interfaces of the multilayer structures. The micro-tubes LSMO and LSMO-NiO have a high flexural strength of ~70 MPa. Cell B with a 3.33 mm outer diameter, a 12 μm LSMO electrolyte layer, a ~300 μm LSMO-NiO functional anode layer, a 9 μm NiO current-collector layer, and a 44 μm La0.6Sr0.4Co0.2Fe0.8O3-δ cathode layer has superior electrochemical performances than does Cell A. The polarization resistance (Rp) value for Cell B accounts for 67.6% and 50.5% of the total resistance (Rt) value at 700 °C and 895 °C, respectively, suggesting that Rp dominates at low temperatures and ohmic resistance (Ro) and Rp values are equally important at high temperatures. Cell B's open-circuit voltages (OCVs) are slightly below the theoretical value due to poor sealing of cells. The maximum power densities (MPDs) of Cell B, increase with increasing operating temperature and are 0.12, 0.24, and 0.27 W cm−2 at 750 °C, 850 °C, and 895 °C, respectively. Compared to Cell A, Cell B displays lower OCV values but higher MPD (0.27 W cm−2 vs. 0.06 W cm−2 at 895 °C) due to its significantly lower Ro value, mainly due to the thin layer of LSMO electrolytes.

  • Design and Evaluation of the Platform for Weight-Shifting Exercises with Compensatory Forces Monitoring
    • Wiktor Sieklicki
    • Robert Barański
    • Szymon Grocholski
    • Patrycja Matejek
    • Mateusz Dyrda
    2020 Pełny tekst Communications in Computer and Information Science

    Details of a platform for the rehabilitation of people with severe balance impairment are discussed in the paper. Based upon a commercially available static parapodium, modified to fit force sensors, this device is designed to give a new, safe tool to physiotherapists. It is designed for the patients who cannot maintain equilibrium during a bipedal stance and need to hold to or lean on something during the rehabilitation. Visual, real-time information about weight distribution between left and right leg as well as the information about the force applied to the pillows supporting the patient's body is provided to the patient with help of a LED display. The control system allows registering forces applied by the patient to the device and analyze them after the therapy. The results of a preliminary evaluation of the device are presented in the paper with four healthy and one Cerebral Palsy ataxic participants. Two exercise scenarios are tested showing significant dependence between balance impairment and compensatory forces measured by the device, as well as a notable difference in how the subject strives for better results if the visual feedback is provided.

  • DESIGN AND THEORETICAL ANALYSIS OF A PROTOTYPE TILTING-PAD RADIAL BEARING WITH ADJUSTABLE CLEARANCE
    • Artur Olszewski
    • Grzegorz Żywica
    • Tomasz Żochowski
    2020 Pełny tekst TRIBOLOGIA

    The article introduces a design and analysis results of a prototype ORC (organic Rankine cycle) turbo generator rotor assembly of 300kW power, supported by tilting-pad bearings of original design. The calculations were performed for a prototype turbo generator rotor. The shaft of this machine is supported with two radial bearings, lubricated with an unusual lubricant – a low-boiling-point agent. The main objective of the presented research was to perform calculations verifying the feasibility of using hydrodynamic tilting-pad radial bearings with a low-viscosity lubricant to support a rather massive and high-speed rotor of the developed turbo generator and to determine the geometry and design of the bearings which would ensure optimal kinetostatic and dynamic properties of the rotating system, while simultaneously providing ease of assembly and smooth clearance adjustment.

  • Design aspects of a low-cost prosthetic arm for people with severe movement disabilities
    • Tomasz Kocejko
    • Radosław Węglarski
    • Tomasz Zubowicz
    • Jacek Rumiński
    • Jerzy Wtorek
    • Krzysztof Armiński
    2020

    In this paper the main aspects of mechanical design behind the low-cost prosthetic arm are presented. The fundamentals of a proper design has been defined to obtain functional 3D printed 5 degree of freedom (DOF) prosthesis. The designed prosthetic arm is a part of the hybrid interface with eye tracking movement control. The main focus was to create affordable but usable prosthesis which corresponds in size and weights to the human arm. The iterative process (starting from the final segment of the arm) was used to design fully functioning arm. All the elements were evaluated regarding total weight and the maximum load that can be carried by the arm. The result of this work is a prototype that weighs below 6kg and has a range of motion comparable to the human's arm. Final product is able to freely move an object of a total weight of 1 kg. All the mechanical parts of the designed arm were 3D printed which therefore presented construction can be adopted by people with different disabilities and (when connected to interfaces like EEG, EMG or eye tracking) provide support in everyday life activities.