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  • Experimental test of nonclassicality with arbitrarily low detection efficiency
    • Alley Hameedi
    • Breno Marque
    • Piotr Mironowicz
    • Debashis Saha
    • Marcin Pawłowski
    • Mohamed Bourennane
    2020 Pełny tekst PHYSICAL REVIEW A

    We theoretically introduce and experimentally demonstrate the realization of a nonclassicality test that allows for arbitrarily low detection efficiency without invoking an extra assumption of independence of the devices. Our test and its implementation is set in a prepare-and-measure scenario with an upper limit on the classical communication capacity of the channel through which the systems are communicated. The essence for our test is the use of two preparation and two measurement devices, which are randomly paired in each round. Our work opens the possibility for experimental realizations of nonclassicality tests with off-the-shelf technology.

  • Explainable AI for Inspecting Adversarial Attacks on Deep Neural Networks
    • Zuzanna Klawikowska
    • Agnieszka Mikołajczyk
    • Michał Grochowski
    2020 Pełny tekst

    Deep Neural Networks (DNN) are state of the art algorithms for image classification. Although significant achievements and perspectives, deep neural networks and accompanying learning algorithms have some important challenges to tackle. However, it appears that it is relatively easy to attack and fool with well-designed input samples called adversarial examples. Adversarial perturba-tions are unnoticeable for humans. Such attacks are a severe threat to the devel-opment of these systems in critical applications, such as medical or military sys-tems. Hence, it is necessary to develop methods of counteracting these attacks. These methods are called defense strategies and aim at increasing the neural mod-el's robustness against adversarial attacks. In this paper, we reviewed the recent findings in adversarial attacks and defense strategies. We also analyzed the ef-fects of attacks and defense strategies applied, using the local and global analyz-ing methods from the family of explainable artificial intelligence.

  • Exploratory analysis and ranking of analytical procedures for short-chain chlorinated paraffins determination in environmental solid samples
    • Mariusz Marć
    • Marta Bystrzanowska
    • Marek Tobiszewski
    2020 Pełny tekst SCIENCE OF THE TOTAL ENVIRONMENT

    Short-chain chlorinated paraffins are ones of the most recent chemical compounds that have been classified as persistent organic pollutants. They have various applications and are emitted to the environment. Despite the fact, that the content levels of these compounds in the environmental compartments should be monitored, there is still a lack of well-defined and validated analytical procedures, proposed or suggested by the national or international environmental protection agencies. Finding an appropriate analytical procedure (sensitive and green at the same time) from many available ones is very often a difficult task. Therefore it can be supported with multicriteria decision analysis. The dataset consisting of 22 procedures was described by 7 criteria, mainly referring to procedures greenness. The data treatment with cluster analysis and principal component analysis revealed the internal structure of the dataset. Moreover, both statistical tools allowed for reduction of dataset criteria to three. This was used for applying ternary plot to show the multicriteria decision analysis results within all possible weights. With the aid of chemometric and multicriteria decision analysis tools it was easy to assess the set of analytical procedure. Depending on the applied weights to assessment criteria different analytical procedures are the most appropriate (winners).

  • Exploring application relationships within enterprise system by matching messages in enterprise log
    • Krzysztof Goczyła
    • Łukasz Korzeniowski
    2020

    With data becoming their key asset, large enterprises require data governance processes to maintain its quality. Because a large portion of business value in enterprise systems is usually delivered by legacy applications without proper documentation, there is a need for a better understanding of these applications and the data produced by them. In this paper, we present an approach to collecting insights into the data managed by enterprise systems by exploring enterprise logs in the search of messages being exchanged between applications. Our method identifies data assets from the extracted messages and finds relationships between them. Based on our professional practice, we verify the method in a generic environment that simulates an enterprise system consisting of applications that exchange XML messages.

  • Exploring Impact of Requirements Engineering on Other IT Project Areas – Case Study
    • Aleksander Jarzębowicz
    • Katarzyna Poniatowska
    2020 Pełny tekst Computer Science

    Requirements Engineering (RE) is recognized as one of the most important (yet difficult) areas of software engineering that has a significant impact on other areas of IT projects and their final outcomes. Empirical studies investigating this impact are hard to conduct, mainly due to the great effort required. It is thus difficult for both researchers and industry practitioners to make evidence-based evaluations about how decisions about RE practices translate into requirement quality and influence other project areas. We propose an idea of a lightweight approach utilizing widely-used tools to enable such an evaluation without extensive effort. This is illustrated with a pilot study where the data from six industrial projects from a single organization were analyzed and three metrics regarding the requirement quality, rework effort, and testing were used to demonstrate the impact of different RE techniques. We also discuss the factors that are important for enabling the broader adoption of the proposed approach.

  • Exploring the Role of Social Media Use Motives, Psychological Well-Being, Self-Esteem, and Affect in Problematic Social Media Use
    • Bruno Schivinski
    • Magdalena Brzozowska-Woś
    • Ellena Stansbury
    • Jason Satel
    • Christian Montag
    • Halley M. Pontes
    2020 Pełny tekst Frontiers in Psychology

    Given recent advances in technology, connectivity, and the popularity of social media platforms, recent literature has devoted great attention to problematic Facebook use. However, exploring the potential predictors of problematic social media use beyond Facebook use has become paramount given the increasing popularity of multiple alternative platforms. In this study, a sample of 584 social media users (Mage = 32.28 years; 67.81% female) was recruited to complete an online survey assessing sociodemographic characteristics, patterns, and preferences of social media use, problematic social media use (PSMU), social media use motives, psychological well-being, self-esteem, and positive and negative affect. Results indicated that 6.68% (n = 39) of all respondents could be potentially classed as problematic users. Moreover, further analysis indicated that intrapersonal motive (β = 0.38), negative affect (β = 0.22), daily social media use (β = 0.18), surveillance motive (β = 0.12), and positive affect (β = −0.09) each predicted PSMU. These variables accounted for about 37% of the total variance in PSMU, with intrapersonal motive driving the greatest predictive contribution, over and above the effects of patterns of social media use and sociodemographic variables. These findings contribute to the increasing literature on PSMU. The results of this study are discussed in light of the existing literature on PSMU.

  • Exploring thiophene-2-acetate and thiophene-3-acetate binding modes towards the molecular and supramolecular structures and photoluminescence properties of Pb(ii) polymers
    • Mateusz Kowalik
    • Joanna Masternak
    • Katarzyna Kazimierczuk
    • Bogumiła Kupcewicz
    • Oleksiy Khavryuchenko
    • Barbara Barszcz
    2020 CRYSTENGCOMM

    To evaluate the impact of the flexible positional isomeric ligands thiophene-2-acetate (2tpacCOO) andthiophene-3-acetate (3tpacCOO) on the construction and self-assembly process of Pb(II) polymers, twonovel compounds, [Pb(2tpacCOO)2(H2O)]n(1) and [Pb(3tpacCOO)2]n(2), were preparedviaanonhydro-thermal method with respect to green chemistry rules. The obtained polymers were fully characterized byelemental analysis, TG/DTG and PXRD, FT-IR, solid-state photoluminescence, DFT calculations and single-crystal X-ray diffraction. Each Pb(II)centreof1is 7-coordinated as a {PbO7} chromophore while the Pb(II)centre of2is 6-coordinated as a {PbO6} structure. The coordination polyhedron of1is best described as adistorted monocapped pentagonal pyramid, and2has a distorted trigonal prismatic shape. The crystallo-graphic analysis and DFT calculations indicated the stereoactivity of the lone electron pair, which contrib-uted to the hemidirected geometry of the Pb(II) environment. Due to the versatile binding modes of the li-gands, complex1forms 1D stair-like chains with an SP 1-periodic net (4,4)(2,0) topology, and theunderlying net of2is determined to have a 1D 2,4C4 topology. It is worth noting that the crystal structuresof the obtained polymers are stabilized mainly by many hydrogen bonds as well as Pb⋯SandPb⋯πtetrelinteractions. Moreover, the PL data demonstrate the different influences of the isomers of linkers onphotoluminescence properties. Polymer1might be a good candidate for obtaining solid-state photo-luminescent materials.

  • Exposure of a small Arctic seabird, the little auk (Alle alle) breeding in Svalbard, to selected elements throughout the course of a year
    • Aneta Pacyna-Kuchta
    • Dariusz Jakubas
    • Marcin Frankowski
    • Żaneta Polkowska
    • Katarzyna Wojczulanis-Jakubas
    2020 Pełny tekst SCIENCE OF THE TOTAL ENVIRONMENT

    The Arctic marine ecosystem can be altered by processes of natural and anthropogenic origin. Spatio-temporal variation in species exposure to contamination is still poorly understood. Here, we studied elemental concentrations in the non-lethally collected samples from the most numerous seabird in European Arctic, the little auk (Alle alle) nesting in one breeding colony in Svalbard. This seabird spent the breeding season in the high-Arctic zone and the non-breeding period in sub-Arctic areas what may implicate spatio-temporal variation in elements bioaccumulation. We determined concentrations of 19 elements in adults feathers to determine levels of exposure during part of the pre-breeding (n = 74) and post-breeding (n = 74) seasons, feathers from nestlings (n=18) to determine local contamination, and chick down (n=16) and post-hatching eggshells (n = 18) to determine maternal input to offspring. During the pre-breeding period adults accumulated in their feathers significantly more Hg (one third of feathers exceeded the established toxicity threshold), Se and Mn compared to the post-breeding period. It reflects a higher exposition of birds to contaminants in pre-breeding moult areas outside the High Arctic compared to the post-breeding moult in the High Arctic. Sex differences in adult feathers representing the post-breeding period were found only for Ca and Zn with higher values in females. Chick down was characterized by high levels of several essential elements, an intermediate level of Hg and Se, and the highest Se:Hg molar ratios of all groups. Chick body feathers had the highest level of Cu and K among all the studied groups. Post-hatching eggshells were characterized by high Sr level (exceeding 2000 μg/g). Concentrations of several non-essential elements (Bi, Cd, Cr, Hg, Ni and Pb) in them were below method detection limits.

  • Exsolution of Ni nanoparticles on the surface of cerium and nickel co-doped lanthanum strontium titanate as a new anodic layer for DIR-SOFC. Anti-coking potential and H2S poisoning resistance of the prepared material
    • Patryk Błaszczak
    • Marcin Łapiński
    • Sea-Fue Wang
    • Piotr Jasiński
    • Beata Bochentyn
    2020 Pełny tekst INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

    The aim of this study was to evaluate a new catalytic material for biogas fueled DIR-SOFC. This material was a perovskite-type SrTiO3 doped with La, Ce and Ni of a general formula La0.27Sr0.54Ce0.09Ni0.1Ti0.9O3-σ (LSCNT). Additional preparation steps were undertaken to promote a nickel exsolution process. Heat post-treatment of powders in a humidified H2 resulted in an intensive growth of nickel nanoparticles (NPs) while the temperature of reduction was increased gradually from 800 to 1200 oC. Selected reduction temperature equal to 900 oC gave NPs of an average size 22 nm. The prepared material was used as a functional layer deposited onto the anodic site of Ni/YSZ supported SOFC to promote an effective reforming of synthetic and H2S-contaminated biogas at 750 oC. It was found that after 130 h of operation in 60% CH4/40% CO2 mixture, the fuel cell with additional LSCNT layer showed higher power density and no carbon deposits were observed. However, 20 ppm of H2S present in fuel caused a full deactivation of both reference and SOFC with LSCNT layer. Cyclic tests in sour biogas revealed that fabricated anodic layer is much more resistant to sulfur poisoning compared to bare Ni/YSZ anode. Recovery of overall performance after 3 poisoning cycles was nearly 90% for a fuel cell with LSCNT layer, while for unmodified one reached only 75%. Concentrations of exhaust gases such as CH4, CO2 and CO were continuously measured in situ using a FTIR-based technique. The thermochemical analysis revealed that investigated material ensures much better biogas reforming stability over whole testing time and strongly promotes catalytic reactions.

  • External Security Strategies of Belarus
    • Krystyna Gomółka
    2020 Pełny tekst Annales Universitatis Mariae-Curie Skłodowska, sectio K – Politologia

    Under President Lukashenko, three Belarusian national security strategies have been announced: the first in 1995, the second in 2001 and the third in 2011. The first proposal, formulated after Lukashenko’s victory in the presidential elections in 1994, outlined Belarus as a neutral state, unbound to any military block in the absence of external enemies. The direction of the foreign policy pursued by the president of Belarus was reflected in the second strategy, where security against NATO and EU member states was sought in a federal state with the Russian Federation. Under the third national security scheme Belarus was to remain in Russia’s military security system. Nevertheless, an important security factor was considered to be the modernisation of the economy with foreign capital participation and the need to diversify the supplies of fuels, thus reducing the country’s dependence on its earlier partner. The subsequently issued documents: the military doctrine of the State, whose assumptions were published on 20 July 2016, and the Concept of security of the Belarusian state borders for the period 2018–2022, prioritised further development of relations with the Russian Federation and the member states of the Collective Security Treaty Organisation. A new element of the 2019 defence plan is the prevention of external aggression and internal disturbance that contribute to the destabilisation of the state.

  • Extractive detoxification of feedstocks for the production of biofuels using new hydrophobic deep eutectic solvents – Experimental and theoretical studies
    • Patrycja Makoś
    • Edyta Słupek
    • Jacek Gębicki
    2020 Pełny tekst JOURNAL OF MOLECULAR LIQUIDS

    The paper presents a synthesis of novel hydrophobic deep eutectic solvents (DESs) composed of natural components, which were used for removal of furfural (FF) and 5-hydroxymethylfurfural (HMF) from lignocellulosic hydrolysates. The main physicochemical properties of DESs were determined, followed by explanation of the DES formation mechanism, using 1H NMR, 13C NMR and FT-IR analysis and density functional theory (DFT). The most important extraction parameters were optimized. Reusability, regeneration of DES, multistage extraction, influence of FF and HMF concentration, as well as possibility of sugars loss were also investigated. The experimental studies revealed high extraction efficiency resulting in 79.2% and 87.9% removal of FF and HMF respectively from model hydrolysates and in the range of 74.2–76.1% and 87.8–82.3% from real samples in one-step extraction. The yield of bio‑hydrogen production via dark fermentation after the DES extraction was comparable to the results obtained using enzymatic hydrolysis. The theoretical studies on the extraction mechanism revealed that hydrogen bonds and van der Waals interactions were the main driving force for detoxification of lignocellulosic biomass.

  • Fabrication of anti-corrosion nitrogen doped graphene oxide coatings by electrophoretic deposition
    • Karolina Ollik
    • Maria Rybarczyk
    • Jakub Karczewski
    • Marek Lieder
    2020 APPLIED SURFACE SCIENCE

    This work assesses anti-corrosion properties of graphene and N-doped graphene coatings deposited on copper by an electrophoretic method. Graphene oxide (GO) precursor was synthesized by an improved Hummers' method, whereas N-doping was performed hydrothermally in the presence of ammonia. After nitrogenation, doped graphene oxide samples (NGO) contained a reduced amount of oxygen and about 9% w/w nitrogen as pyridinic, pyrrole, and graphitic groups. Nevertheless, it was possible to obtain a stable aqueous dispersion of NGOs, a prerequisite for the EPD process. According to SEM images, the EPD coatings were compact with minor defects. On the contrary, GO coating possessed cracks and large pores that resulted from gas evolution during electrolysis. Electrochemical studies showed that all coatings prevented copper from corrosion in saline solution, however, the nitrogenated coatings did not exhibit better anti-corrosion properties than reduced graphene oxide coating. A reasonable explanation of this finding is that some positive properties of the nitrogenated coatings, in terms of anti-corrosion action, like low hydrophilicity and good adhesion, were counteracted by their catalytic activity towards oxygen reduction reaction.

  • Fabrication of Durable Ordered Ta2O5 Nanotube Arrays Decorated with Bi2S3 Quantum Dots
    • Mateusz Baluk
    • Marek Kobylański
    • Wojciech Lisowski
    • Grzegorz Trykowski
    • Tomasz Klimczuk
    • Marek Mazierski
    • Adriana Zaleska-Medynska
    • Mateusz Adam Baluk
    2020 Pełny tekst Nanomaterials

    One of the most important challenges in the fabrication of ordered tantalum pentaoxide (Ta2O5) nanotube arrays (NTs) via the electrochemical method is the formation of nanotubes that adhere well to the Ta substrate. In this paper, we propose a new protocol that allows tight-fitting Ta2O5 nanotubes to be obtained through the anodic oxidation of tantalum foil. Moreover, to enhance their activity in the photocatalytic reaction, in this study, they have been decorated by nontoxic bismuth sulfide (Bi2S3) quantum dots (QDs) via a simple successive ionic layer adsorption and reaction (SILAR) method. Transmission electron microscopy (TEM) analysis revealed that quantum dots with a size in the range of 6-11 nm were located both inside and on the external surfaces of the Ta2O5 NTs. The effect of the anodization time and annealing conditions, as well as the effect of cycle numbers in the SILAR method, on the surface properties and photoactivity of Ta2O5 nanotubes and Bi2S3/Ta2O5 composites have been investigated. The Ta2O5 nanotubes decorated with Bi2S3 QDs exhibit high photocatalytic activity in the toluene degradation reaction, i.e., 99% of toluene (C0 = 200 ppm) was degraded after 5 min of UV-Vis irradiation. Therefore, the proposed anodic oxidation of tantalum (Ta) foil followed by SILAR decorating allows a photocatalytic surface, ready to use for pollutant degradation in the gas phase, to be obtained.

  • Fabrication of exfoliated graphite reinforced silicone rubber composites - Mechanical, tribological and dielectric properties
    • Józef Haponiuk
    • P. S. Sarath
    • Sohil Vargese Samson
    • Rakesh Reghunath
    • Mrituanjay Kumar Pandey
    • Sabu Thomas
    • Soney C. George
    2020 Pełny tekst POLYMER TESTING

    The effect of exfoliated graphite (EG) on the mechanical, tribological and dielectric properties of the silicone rubber (QM) composites has been systematically investigated and analysed. Morphological analysis of the composites helps to understand the interfacial interaction between the filler and the rubber matrix as well as wear mechanism respectively. An enhancement in the mechanical, tribological and dielectric properties was observed with an increase in filler loading and better performance was observed at 7 phr of filler loading. The improvement in performance is attributed to the better interaction between the QM chains and the EG layers as evident from the AFM and TEM analysis. It is also evident from the Kraus plot which supports the reinforcing effect of EG in QM matrix.

  • Fabrication of exfoliated graphite reinforced silicone rubber composites - Mechanical, tribological and dielectric properties
    • P. S. Sarath
    • Sohil Vargese Samson
    • Rakesh Reghunath
    • Mrituanjay Kumar Pandey
    • Józef Haponiuk
    • Sabu Thomas
    • Soney C. George
    2020 Pełny tekst POLYMER TESTING

    The effect of exfoliated graphite (EG) on the mechanical, tribological and dielectric properties of the silicone rubber (QM) composites has been systematically investigated and analysed. Morphological analysis of the composites helps to understand the interfacial interaction between the filler and the rubber matrix as well as wear mechanism respectively. An enhancement in the mechanical, tribological and dielectric properties was observed with an increase in filler loading and better performance was observed at 7 phr of filler loading. The improvement in performance is attributed to the better interaction between the QM chains and the EG layers as evident from the AFM and TEM analysis. It is also evident from the Kraus plot which supports the reinforcing effect of EG in QM matrix.

  • Fabrication of ILs-Assisted AgTaO3 Nanoparticles for the Water Splitting Reaction: The Effect of ILs on Morphology and Photoactivity
    • Julia Zwara
    • Anna Pancielejko
    • Marta Paszkiewicz-Gawron
    • Justyna Łuczak
    • Magdalena Miodynska
    • Wojciech Lisowski
    • Adriana Zaleska-Medynska
    • Ewelina Grabowska-Musiał
    2020 Pełny tekst Materials

    The design of an active, stable and ecient photocatalyst that is able to be used for hydrogen production is of great interest nowadays. Therefore, four methods of AgTaO3 perovskite synthesis, such as hydrothermal, solvothermal, sol-gel and solid state reactions, were proposed in this study to identify the one with the highest hydrogen generation eciency by the water splitting reaction. The comprehensive results clearly show that the solid state reaction (SSR) led to the obtainment of a sample with an almost seven times higher photocatalytic activity than the other methods. Furthermore, four ionic liquids, all possessing nitrogen in the form of organic cations (two imidazoliums with dierent anions, ammonium and tetrazolium), were used for the first time to prepare composites consisting of AgTaO3 modified with IL and Pt, simultaneously. The eect of the ionic liquids (ILs) and Pt nanoparticles’ presence on the structure, morphology, optical properties, elemental composition and the eectiveness of the hydrogen generation was investigated and discussed. The morphology investigation revealed that the AgTaO3 photocatalysts with the application of [OMIM]-cation based ILs created smaller granules (<500 nm), whereas [TBA] [Cl] and [TPTZ] [Cl] ILs caused the formation of larger particles (up to 2 m). We found that various ILs used for the synthesis did not improve the photocatalytic activity of the obtained samples in comparison with pristine AgTaO3. It was detected that the compound with the highest ability for hydrogen generation under UV-Vis irradiation was the AgTaO3_0.2% Pt (248.5 molg1), having an almost 13 times higher eciency in comparison with the non-modified pristine sample. It is evidenced that the enhanced photocatalytic activity of modified composites originated mainly from the presence of the platinum particles. The mechanism of photocatalytic H2 production under UV-Vis light irradiation in the presence of an AgTaO3_IL_Pt composite in the water splitting reaction was also proposed.

  • Facebook, YouTube, Instagram... jako arbitrzy prawdy. Deepfake – na szlaku dystopii i łasce korporacji
    • Jan Kreft
    2020

    Zidentyfikowano ich w 2019 roku w sieci blisko 15 tysięcy . Zwykle nie dotyczą polityki, choć to przede wszystkim w środowisku politycznym budzą strach i zwątpienie. Strach przed dewastacja resztek społecznego zaufania, jakimi politycy się cieszą, zwątpienie – bo zwalczanie ich przekracza polityczne możliwości władz ujmowanych w kartezjańskim podziale władzy. Deepfake – bo o nich mowa – są przełomową innowacją wyznaczającą nowe granice możliwości poznawczych ludzi w cyfrowym środowisku, technologią która wykorzystywana jest z różnymi intencjami, od „mowy (wideo) nienawiści”, po szczytne kampanie społeczne i kładzie podwaliny pod „koniec prawdy” w mediach. Ich identyfikacja i usuwanie ukazuje kluczowy problem współczesnego zarządzania organizacjami mediano – technologicznymi w relacjach z otoczeniem. Jest nową odsłoną asymetrii zależności między użytkownikiem, a organizacją - platformą nowomedialną, nowej relacji władzy i konieczności zdania się na dobrą wolę, determinację oraz potencjał badawczy organizacji medialno – technologicznych.

  • Factors Affecting the Effectiveness of Military Training in Virtual Reality Environment
    • Małgorzata Gawlik-Kobylińska
    • Paweł Maciejewski
    • Jacek Lebiedź
    • Aneta Wysokińska-Senkus
    2020

    In this paper, we explored the factors influencing the effectiveness of military trainings performed in a virtual reality environment. The rationale for taking up the topic is the fact that such trainings are often conducted under specific operational procedures. These procedures may create rigorous frameworks for all elements of the learning environment, including the teacher’s performance. Therefore, to ensure the most conducive conditions of training and, thus, its effectiveness, it is necessary to identify critical factors to be taken into account while designing the training process. On the basis of literature review, we selected, analysed, and categorized the most relevant factors concerning the learner, the teacher, as well as didactic tools and the content. We limited our considerations to the learning environment and the teaching process. We did not explore the organizational level. Another implication concerns the development of a tool for training effectiveness assessment based on the identified factors.

  • Factors of successful client co-production in knowledge-intensive business services
    • Małgorzata Zięba
    • Paweł Kończyński
    2020 Pełny tekst KYBERNETES

    Purpose This paper aims to explore the topic of client co-production in knowledge-intensive business services (KIBS). The paper first sketches a theoretical background and reviews previous studies on factors affecting successful client co-production in such companies and then examines these factors via case study research among a small KIBS company and its five customers. Design/methodology/approach The paper is based on an in-depth analysis of literature devoted to client co-production in KIBS firms and on the results of case studies analysis. The authors explore theoretically and empirically the perception of factors behind a successful client co-production process of a KIBS company from the point of view of both customers and service provider. The examination resulted in the clarification of what a successful client-KIBS firm cooperation should look like and what kind of actions KIBS firms should undertake to provide it. Findings As the analysis shows, to perceive client-KIBS firm cooperation as successful, customers desire on hand immediate effects that would justify and compensate their time and money investments (e.g. new clients or brand recognition) and on the other hand, some of them desire positive changes in longer-term, which tangible form is associated with the newly obtained knowledge and more importantly, freshly developed and written strategy. Among the factors that influence the co-production process one can list teamwork, trust, communication and knowledge flows. Research limitations/implications Research results are limited to one KIBS company operating in Poland and its five customers. As such, they are not conclusive for the whole KIBS sector. The findings of both literature review and case study analysis indicate that there are several outcomes that are expected from the point of view of a KIBS customer when selecting the service of a KIBS company. The paper examines important aspect of service co-production and provides practical guidelines how cooperation between KIBS firms and their customers should look like. Practical implications The paper examines the relationship between a client and a KIBS company and explores the factors influencing the successful outcome of this relation. The paper provides guidelines on how this type of relation should be handled by managers or owners of KIBS firms.

  • Failures and a concept of corrosion protection system for spiral classifiers at KGHM Polska Miedź S.A. Ore Concentration Plant
    • Marcin Czekajło
    • Krzysztof Żakowski
    2020 Pełny tekst ENGINEERING FAILURE ANALYSIS

    The Ore Concentration Plant, where the process of flotation is carried out as well as the final production of copper concentrate, plays a key role in the entire production line of KGHM Polska Miedź S.A. Majority of operations related to the run-of-mine preparation to copper flotation enrichment are carried out in a water environment. The maintaining of production process continuity requires to pursue minimisation of many production limitations. The corrosive action of the technological medium, being a salted water suspension of ground copper ore, is one of them. The concept of spiral classifiers cathodic protection presented in this paper may become an alternative to the anti-corrosion protection methods of machinery and equipment used now at the KGHM. The obtained results of research indicate a possibility of significant reduction of classifiers corrosion rate at the application of cathodic protection and of a few times extension of the period of spiral classifiers operation, which replacement generates substantial operating costs.

  • Falowniki napięcia z quasi-rezonansowym obwodem pośredniczącym w układach napędowych
    • Marek Turzyński
    2020

    W monografii przedstawiono zagadnienia związane z wykorzystaniem pośrednich przemienników częstotliwości z rezonansowymi oraz quasi-rezonansowymi obwodami pośredniczącymi w układach napędowych. Omówiono wpływ przełączania „twardego” przy niezerowych prądach i napięciach łączników na właściwości eksploatacyjne elektrycznego układu napędowego. Ponadto dokonano przeglądu wybranych topologii przekształtników DC/AC, zapewniających techniki „miękkiego” przełączania łączników w stanach bezprądowych lub beznapięciowych. Omówiono mechanizm powstawania składowych napięć wspólnych oddziałujących na silnik elektryczny i związane z nimi zjawisko prądów łożyskowych, a także przedstawiono wyniki eksperymentalnej weryfikacji skuteczności powszechnie stosowanych metod tłumienia składowych napięcia wspólnego w układach falowników napięcia z komutacją twardą. W ramach monografii zaproponowano autorską strukturę falownika napięcia z quasi-rezonansowym obwodem pośredniczącym, umożliwiającą redukcję poziomów napięć wspólnych, ograniczenie wielkości prądów doziemnych oraz poprawę warunków zasilania maszyny elektrycznej, co zostało pozytywnie zweryfikowane w przeprowadzonych badaniach eksperymentalnych.

  • Family business succession – the practical or also theoretical problem. Bibliometric analysis
    • Marzena Grzesiak
    2020

    Family businesses, in various forms, have existed since societies began to be created. However, family business research has a decidedly shorter tradition. In favorable conditions, family enterprises develop for many generations, and their fate is intertwined with the fate of the families. The topics of family businesses are raised by researchers around the world. Estimates regarding the number of family businesses are a frequent subject of scientific disputes. Differences in the results of scientific research result, among others, from a different understanding of the concept of family accessibility. This requires uniformity in decisions regarding the definitions of this term. Most family businesses are micro and small service companies, but there are also many large family enterprises in the world (e.g. Anderson R., Reeb D 2003: in the US, families control 1/3 of the richest companies comprising the S&P 500 index). The averaged international stock exchange estimates show that about 44% of the listed companies are in the hands of families. In the USA and Canada, the share of family businesses in the population is estimated at 80–90%, while in Europe — at around 75%. The aim of this chapter is to analyze the directions of research in the field of family businesses with particular attention to the process of succession. This goal will be achieved through a review of articles dedicated to family businesses as well as through the usage of bibliometric analysis tools. The work starts with a general review of the literature concerning the issues of family businesses, in order to indicate the main trends of research. Next, the results of reports dealing with the problem of statistics of family enterprises are presented, focusing on the succession issue. Bibliometric research has been used for the synthetic analysis of publications addressing the succession and made it possible to search for the regularity in the structure of scientific achievements in this field. The author used two bibliometric methods. On the basis of standard indicators generated by the tools offered by Scopus, a descriptive analysis of the publication structure was made. Next, in order to identify the main research topics, the analysis of the co-occurrence of words was carried out using the Vosviewer tool.

  • Fast Antenna Optimization Using Gradient Monitoring and Variable-Fidelity EM Models
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2020 APPLIED COMPUTATIONAL ELECTROMAGNETICS SOCIETY JOURNAL

    Accelerated simulation-driven design optimization of antenna structures is proposed. Variable-fidelity electromagnetic (EM) analysis is used as well as the trust-region framework with limited sensitivity updates. The latter are controlled by monitoring the changes of the antenna response gradients. Our methodology is verified using three compact wideband antennas. Comprehensive benchmarking demonstrates its superiority over both conventional and surrogate-assisted algorithms.

  • Fast Fading Characterization for Body Area Networks in Circular Metallic Indoor Environments
    • Filipe D. Cardoso
    • Paweł Kosz
    • Manuel M. Ferreira
    • Sławomir Ambroziak
    • Luis M. Correia
    2020 Pełny tekst IEEE Access

    With the increasing development of 5G and Body Area Network based systems being implemented in unusual environments, propagation inside metallic structures is a key aspect to characterize propagation effects inside ships and other similar environments, mostly composed of metallic walls. In this paper, indoor propagation inside circular metallic structures is addressed and fast fading statistical distributions parameters are obtained from simulation, being assessed with measurements at 2.45 GHz in a passenger ferry discotheque with an 8 m diameter circular shape. It is observed that, in this kind of environments, second order reflections are particularly relevant due to the walls’ high reflective nature. Globally, it is concluded that the Rayleigh distribution can be used to characterize fast fading effects with no significant loss of accuracy compared to the Rice one, since a low value of the Rice parameter is observed, being below 3.1 dB, even under Line-of-Sight conditions. Moreover, it is observed that, from the fast fading viewpoint, the best transmitter position is at the circle center.

  • Fast Multi-Objective Aerodynamic Optimization Using Sequential Domain Patching and Multifidelity Models
    • Anand Amrit
    • Leifur Leifsson
    • Sławomir Kozieł
    2020 Pełny tekst JOURNAL OF AIRCRAFT

    Exploration of design tradeoffs for aerodynamic surfaces requires solving of multi-objective optimization (MOO) problems. The major bottleneck here is the time-consuming evaluations of the computational fluid dynamics (CFD) model used to capture the nonlinear physics involved in designing aerodynamic surfaces. This, in conjunction with a large number of simulations necessary to yield a set of designs representing the best possible tradeoffs between conflicting objectives (referred to as a Pareto front), makes CFD-driven MOO very challenging. This paper presents a computationally efficient methodology aimed at expediting the MOO process for aerodynamic design problems. The extreme points of the Pareto front are obtained quickly using single-objective optimizations. Starting from these extreme points, identification of an initial set of Pareto-optimal designs is carried out using a sequential domain patching algorithm. Refinement of the Pareto front, originally obtained at the level of the low-fidelity CFD model, is carried out using local response surface approximations and adaptive corrections. The proposed algorithm is validated using a few multi-objective analytical problems and an aerodynamic problem involving MOO of two-dimensional transonic airfoil shapes where the figures of interest are the drag and pitching moment coefficients. A multifidelity model is constructed using CFD model and control points parameterizing the shape of the airfoil. The results demonstrate that an entire or a part of the Pareto front can be obtained at a low cost when considering up to eight design variables.

  • Fast multi-objective design optimization of microwave and antenna structures using data-driven surrogates and domain segmentation
    • Sławomir Kozieł
    • Adrian Bekasiewicz
    2020 Pełny tekst ENGINEERING COMPUTATIONS

    Purpose Strategies and algorithms for expedited design optimization of microwave and antenna structures in multi-objective setup are investigated. Design/methodology/approach Formulation of the multi-objective design problem oriented towards execution of the population-based metaheuristic algorithm within the segmented search space is investigated. Described algorithmic framework exploit variable fidelity modeling, physics- and approximation-based representation of the structure, as well as model correction techniques. The considered approach is suitable for handling various problems pertinent to design of microwave and antenna structures. Numerical case studies are provided demonstrating feasibility of the segmentation-based framework for design of real-world structures in setups with two and three objectives. Findings Formulation of appropriate design problem enables identification of the search space region containing Pareto front which can be further divided into a set of compartments characterized by small combined volume. Approximation model of each segment can be constructed using a small number of training samples and then optimized, at a negligible computational cost, using population-based metaheuristics. Introduction of segmentation mechanism to multi-objective design framework is important to facilitate low cost optimization of many-parameter structures represented by numerically expensive computational models. Further reduction of the design cost can be achieved by enforcing equal-volumes of the search space segments. Research limitations/implications The study summarizes recent advances in low-cost multi-objective design of microwave and antenna structures. The investigated techniques exceed capabilities of conventional design approaches involving direct evaluation of physics-based models for determination of trade-offs between the design objectives, particularly in terms of reliability and reduction of the computational cost. Studies on scalability of segmentation mechanism indicate that computational benefits of the approach decrease with the number of search space segments.

  • Fast multi-objective optimization of antenna structures by means of data-driven surrogates and dimensionality reduction
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2020 Pełny tekst IEEE Access

    Design of contemporary antenna structures needs to account for several and often conflicting objectives. These are pertinent to both electrical and field properties of the antenna but also its geometry (e.g., footprint minimization). For practical reasons, especially to facilitate efficient optimization, single-objective formulations are most often employed, through either a priori preference articulation, objective aggregation, or casting all but one (primary) objective into constraints. Notwithstanding, the knowledge of the best possible design trade-offs provides a more comprehensive insight into the properties of the antenna structure at hand. Genuine multi-objective optimization is a proper way of acquiring such data, typically rendered in the form of a Pareto set that represents the mentioned trade-off solutions. In antenna design, the fundamental challenge is high computational cost of multi-objective optimization, normally carried out using population-based metaheuristic algorithms. In most practical cases, the use of reliable, yet costly, full-wave electromagnetic models is imperative to ensure evaluation reliability, which makes conventional multi-objective optimization procedures prohibitively expensive. The employment of fast surrogates (or metamodels) can alleviate these difficulties, yet, construction of metamodels faces considerable challenges by itself, mostly related to the curse of dimensionality. This work proposes a novel surrogate-assisted approach to multi-objective optimization, where the data-driven model is only rendered in a small region spanned by the selected principal components of the extreme Pareto-optimal design set obtained using local search routines. The region is limited in terms of parameter ranges but also dimensionality, yet contains the majority of Pareto front, therefore surrogate construction therein does not incur considerable costs. The typical cost of identifying the Pareto set is just a few hundred of full-wave analyses of the antenna under design. Our technique is validated using two antenna examples (a planar Yagi and an ultra-wideband monopole antenna) and favorably compared to state-of-the-art surrogate-assisted multi-objective optimization methods.

  • Fast-response optoelectronic detection of explosives’ residues from the nitroaromatic compounds detonation: field studies approach
    • Jacek Wojtas
    • Robert Bogdanowicz
    • Agata Kamieńska-Duda
    • Beata Pietrzyk
    • Michał Sobaszek
    • Piotr Prasuła
    • Anna Dettlaff
    • Krzystof Achtenberg
    2020 Pełny tekst MEASUREMENT

    We are presenting an application of optoelectronic nitrogen dioxide (NO2) analyzer based on cavity enhanced absorption spectroscopy in the detection of traces of explosives after detonation. It has been shown that the analyzer using blue-violet laser is able to detect explosive residues after the detonation of various amounts of nitroaromatic compounds (75g-1kg) with higher efficiency than the HPLC soil sample testing equipment, which is the common standard in the analysis of explosives. Field studies have shown that it provided quick results, the amplitudes of which were about 8 dB despite the fact that NO2 in the air was 3 orders of magnitude smaller than explosives found in soil. The NO2 concentration after an explosion of different explosives at the distance of up to 20 m from the crater was 21-137 ppb, which was also dependent on the time between the explosion and the measurement, temperature and humidity of the atmospheric air and wind speed.

  • Fault Diagnostics in PEMFC Stacks by Evaluation of Local Performance and Cell Impedance Analysis
    • Jens Mitzel
    • J. Sanchez‐Monreal
    • D. Garcia‐Sanchez
    • P. Gazdzicki
    • M. Schulze
    • F. Häußler
    • Jurgen Hunger
    • G. Schlumberger
    • Ewa Janicka
    • Michał Mielniczek
    • Łukasz Gaweł
    2020 FUEL CELLS

    Starvation, flooding, and dry‐out phenomena occur in polymer electrolyte membrane fuel cells (PEMFCs), due to heterogeneous local conditions, material inhomogeneity, and uneven flow distribution across the single cell active area and in between the individual cells. The impact of the load level and air feed conditions on the performance was identified for individual single cells within a 10‐cell stack. Analysis of the current density distribution across the active area at the cell level was correlated with electrochemical impedance spectroscopy to enable operando fault diagnostic without any impact of the applied analytical tools on the single cell behavior. Moreover, the combination of both technologies allows in‐depth analysis of fault mechanisms in fuel cell single cells with improved sensitivity. Current density distribution and the quantitative assessment of the performance homogeneity demonstrated high sensitivity to small humidity changes and allow the detection of critical events, such as dry‐out in single cells. Impedance analysis is more sensitive regarding polarization and diffusion limitations and allows detection of cell flooding. The combination of both techniques is required for reliable identification of air starvation faults.

  • Fault Loop Impedance Measurement in Circuits Fed by UPS and Principle of Safety Protection
    • Jacek Katarzyński
    • Marek Olesz
    2020 Pełny tekst Sustainability

    This paper indicates a significant problem of uncertainty of fault loop impedance (FLI) measurement in circuits powered from uninterruptible power supply (UPS) (double-conversion AC-DC-AC). The correctly determined value of this impedance, related to the short-circuit current disconnection time and to the reference value, is one of the most important elements that determines the approval of an electrical installation and its receivers for operation. To define the principles of FLI measurement, several hundred measurements of the short-circuit loop impedance in the circuits fed by the UPS, in various UPS operation modes and with various FLI instruments, were made, which allowed for the definition of measurement rules that reduce the error in assessing the effectiveness of protection against electric shock by automatic disconnection of supply. Based on the analysis of voltage and current waveforms recorded during the real short-circuit tests in the circuit fed by the UPS, a proprietary algorithm for determining the short-circuit loop impedance has been proposed.

  • Faults and Fault Detection Methods in Electric Drives
    • Patrick Strankowski
    • Jarosław Guziński
    2020

    The chapter presents a review of faults and fault detection methods in electric drives. Typical faults are presented that arises for the induction motor, which is valued in the industry for its robust construction and cost-effective production. Moreover, a summary is presented of detectable faults in conjunction with the required physical information that allow a detection of specific faults. In order to address faults of a complete drive system, characteristic failures of the mechanical part of the drive system are as well presented. Furthermore, the physical forces, which arise during specific faults (i.e. centrifugal, kinematic) are presented along with dominant harmonics in the frequency spectrum. These dominant harmonics are especially important for the determination of a malfunction of the drive. The detection of the particular could be performed with signal processing methods which are tabular summarized for introduction purposes. In order to cover a further industry interest, a cost-effectiveness relation is presented, which describes whether a diagnostic system is appreciative or not. Moreover, most important international standards regarding the safety, health for human and machinery are summarized that are required to be fulfilled in every industrial application. The next subsection is dedicated to the presentation of fault detection methods that include a review of conventional methods for monitoring the conditions of the electric machine. That includes the monitoring of variables that are based on electrical, chemical, mechanical and thermal changes in the induction motor. The last subsection considers the fault detection methods, which are based on utilization of mathematical models. In this kind of fault detection, the model description is utilized to identify changes in the drive system, which then can be used for a potential fault identification procedure. Such mathematical constructs are mainly based on observer, Kalman filters or neural networks. The chapter is concluded with a short summary of the presented sections.

  • Feasibility Study GaN Transistors Application in the Novel Split-Coils Inductive Power Transfer System with T-Type Inverter
    • Viktor Shevchenko
    • Bohdan Pakhaliuk
    • Oleksandr Husev
    • Oleksandr Veligorskyi
    • Deniss Stepins
    • Ryszard Strzelecki
    2020 Pełny tekst ENERGIES

    A promising solution for inductive power transfer and wireless charging is presented on the basis of a single-phase three-level T-type Neutral Point Clamped GaN-based inverter with two coupled transmitting coils. The article focuses on the feasibility study of GaN transistor application in the wireless power transfer system based on the T-type inverter on the primary side. An analysis of power losses in the main components of the system is performed: semiconductors and magnetic elements. System modeling was performed using Power Electronics Simulation Software (PSIM). It is shown that the main losses of the system are static losses in the filter inductor and rectifier diodes on the secondary side, while GaN transistors can be successfully used for the wireless power transfer system. The main features of the Printed Circuit Board (PCB) design of GaN transistors are considered in advance

  • Feedback Control of Multiphase Induction Machines with Backstepping Technique
    • Marcin Morawiec
    • Patrick Strankowski
    • Arkadiusz Lewicki
    • Jarosław Guziński
    • Filip Wilczyński
    2020 IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS

    The paper presents the control possibility of five phase induction machines. In the proposed solution the machine model vector form is not transformed to the (dq)-coordinate system, that is connected to rotor flux vector, but utilizes the stationary system ( αβ ). Moreover, the nonlinear model linearization is based on demonstrated nonlinear variables transformation for i-orthogonal ( αβ )(n) planes. By introducing the backstepping approach, the independent stabilization of electromagnetic torque and rotor flux in each plane is obtained. A practical stability analysis of the proposed controller for a multi-phase machine is illustrated as well. Finally, experimental test results are demonstrated for a specific speed sensorless five phase induction motor test setup

  • FEM-based wave propagation modelling for SHM: Certain numerical issues in 1D structures
    • Magdalena Palacz
    • Arkadiusz Żak
    • Marek Krawczuk
    2020 Pełny tekst Materials

    The numerical modelling of structural elements is an important aspect of modern diagnostic systems. However, the process of numerical implementation requires advanced levels of consideration of multiple aspects. Important issues of that process are the positive and negative aspects of solution applied methods. Therefore the aim of this article is to familiarise the reader with the most important aspects related to the process of numerical modelling of one-dimensional problems related to the phenomena of the propagation of elastic waves and their application for damage detection purposes.

  • Filozofować z głębi człowieczeństwa. O fenomenologii Andrzeja Półtawskiego.
    • Andrzej Lisak
    2020 Kwartalnik Filozoficzny

    Dokonując krytyki tradycji nowożytnego empiryzmu i kartezjańskiego dualizmu Półtawski tworzy realistyczną i dynamiczną interpretację bytu ludzkiego. Przeżywanie, odczuwanie zmysłowe nie jest poślednią odmianą poznania jak i operacją dostarczania jedynie elementów, budulca poznaniu, ale odrębnym sposobem bycia w świecie, jest symbiotycznym kontaktem z otoczeniem, formą życia. Zrywa on radykalnie z tradycją brentanowsko-husserlowską traktowania świadomości jako zbioru aktów, a nie zbioru treści. Przeciwstawia temu model fenomenologii noematycznej. Nie możemy zobaczyć jak powstają noematy (treści świadomości), bo nie jest to robota samej świadomości, ani w sferze zmysłowego przeżywania, gdzie świat jest nam już pierwotnie dany jakby „od dołu” ani na wyższym poziomie świadomego funkcjonowania w świecie, gdzie świat (jako model świata), jest już nam znowuż dany, jakby „od góry”. Model świata tkwi nie w świadomości aktualnie obecnej, ale jakby za jej kulisami, aby umożliwić przytomne bycie człowieka w świecie. Ontologia wypracowana na gruncie najprostszego sposobu bycia człowieka jako tylko postrzegającego nie jest w stanie pojąć i zrozumieć realności świata, a zwłaszcza realności wartości. Oddać sprawiedliwość roli wartości może tylko całościowa i dynamiczna koncepcja człowieka, której wizji Półtawski szuka w konfrontacji z poglądami Ingardena , Strassera i Wojtyły.

  • Finiper
    • Luciano Segreto
    2020

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  • Finite Element Approaches to Model Electromechanical, Periodic Beams
    • Wiktor Waszkowiak
    • Marek Krawczuk
    • Magdalena Palacz
    2020 Pełny tekst Applied Sciences-Basel

    Periodic structures have some interesting properties, of which the most evident is the presence of band gaps in their frequency spectra. Nowadays, modern technology allows to design dedicated structures of specific features. From the literature arises that it is possible to construct active periodic structures of desired dynamic properties. It can be considered that this may extend the scope of application of such structures. Therefore, numerical research on a beam element built of periodically arranged elementary cells, with active piezoelectric elements, has been performed. The control of parameters of this structure enables one for active damping of vibrations in a specific band in the beam spectrum. For this analysis the authors propose numerical models based on the finite element method (FEM) and the spectral finite element methods defined in the frequency domain (FDSFEM) and the time domain (TDSFEM).

  • Finite element modelling of a historic church structure in the context of a masonry damage analysis
    • Marcin Kujawa
    • Izabela Lubowiecka
    • Czesław Szymczak
    2020 Pełny tekst ENGINEERING FAILURE ANALYSIS

    The paper includes a case study of modelling a real historic church using the finite element method (FEM) based on laser scans of its geometry. The main goal of the study was the analysis of the causes of cracking and crushing of masonry walls. An FEM model of the structure has been defined in ABAQUS. A non-linear dynamic explicit analysis with material model including damage plasticity has been performed. A homogenization procedure has been applied to obtain the material parameters used in the modelling of masonry. In the numerical analysis, the interactions between the church structure, the foundations and the ground were taken into account. The obtained results match well with the damaged area of the entire structure from the in-situ survey, and it should be highlighted that the proposed FEM model allows for a rather precise identification of the causes and effects of cracking walls in a qualitative sense. Also a brief research summary is presented.

  • Fish gelatin films containing aqueous extracts from phenolic-rich fruit pomace
    • Hanna Staroszczyk
    • Barbara Kusznierewicz
    • Edyta Malinowska-Pańczyk
    • Izabela Sinkiewicz
    • Karolina Gottfried
    • Ilona Kołodziejska
    2020 Pełny tekst LWT-FOOD SCIENCE AND TECHNOLOGY

    The aim of the work was to study the feasibility of using aqueous extracts from rowanberry, blue-berried honeysuckle, and chokeberry pomace for the formulation of fish gelatin films with antioxidant and antimicrobial activity as well as improved mechanical and water barrier properties. The predominant phenolic components in rowanberry and chokeberry extracts were hydroxycinnamates, and in blue-berried honeysuckle extract antho cyanins. Although the gelatin film itself showed antioxidative activity, addition of blue-berried honeysuckle extract increased it 3-fold. Unlike the films containing 1.2 mL of extract, the films with increased extract volume possessed strong antimicrobial properties against E. coli, P. fluorescens, S. aureus, L. innocua. Films plasticized with glycerol at 15 and 17.5% did not increase the mechanical strength in the presence of all extracts tested, but at 20%, a positive effect of each extract on mechanical strength was observed. None of the extracts affected the water barrier properties of the films.

  • Fixed Pattern Noise Reduction and Linearity Improvement in Time-Mode CMOS Image Sensors
    • Miron Kłosowski
    • Yichuang Sun
    2020 Pełny tekst SENSORS

    In the paper, a digital clock stopping technique for gain and offset correction in time-mode analog-to-digital converters (ADCs) has been proposed. The technique is dedicated to imagers with massively parallel image acquisition working in the time mode where compensation of dark signal non-uniformity (DSNU) as well as photo-response non-uniformity (PRNU) is critical. Fixed pattern noise (FPN) reduction has been experimentally validated using 128-pixel CMOS imager. The reduction of the PRNU to about 0.5 LSB has been achieved. Linearity improvement technique has also been proposed, which allows for integral nonlinearity (INL) reduction to about 0.5 LSB. Measurements confirm the proposed approach.

  • Flexoelectricity and apparent piezoelectricity of a pantographic micro-bar
    • Victor Eremeev
    • Jean-François Ganghoffer
    • Violetta Konopińska-Zmysłowska
    • Nikolay Uglov
    2020 Pełny tekst INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE

    We discuss a homogenized model of a pantographic bar considering flexoelectricity. A pantographic bar consists of relatively stiff small bars connected by small soft flexoelectric pivots. As a result, an elongation of the bar relates almost to the torsion of pivots. Taking into account their flexoelectric properties we find the corresponding electric polarization. As a results, the homogenized pantographic bar demonstrates piezoelectric properties inherited from the flexoelectric properties of pivots. The effective stiffness properties of the homogenized bars are determined by the geometry of the structural elements and shear stiffness whereas the piezoelectric properties follow from the flexoelectric moduli of the pivots.

  • Flexural behavior of composite structural insulated panels with magnesium oxide board facings
    • Łukasz Smakosz
    • Ireneusz Kreja
    • Zbigniew Pozorski
    2020 Pełny tekst Archives of Civil and Mechanical Engineering

    The current report is devoted to the flexural analysis of a composite structural insulated panel (CSIP) with magnesium oxide board facings and expanded polystyrene (EPS) core, that was recently introduced to the building industry. An advanced nonlinear FE model was created in the ABAQUS environment, able to simulate the CSIP’s flexural behavior in great detail. An original custom code procedure was developed, which allowed to include material bimodularity to significantly improve the accuracy of computational results and failure mode predictions. Material model parameters describing the nonlinear range were identified in a joint analysis of laboratory tests and their numerical simulations performed on CSIP beams of three different lengths subjected to three- and four-point bending. The model was validated by confronting computational results with experimental results for natural scale panels; a good correlation between the two results proved that the proposed model could effectively support the CSIP design process.

  • Flooding Extent Mapping for Synthetic Aperture Radar Time Series Using River Gauge Observations
    • Tomasz Berezowski
    • Tomasz Bieliński
    • Jakub Osowicki
    2020 Pełny tekst IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing

    The flooding extent area in a river valley is related to river gauge observations such as discharge and water elevations. The higher the water elevations, or discharge, the larger the flooding area. Flooding extent maps are often derived from synthetic aperture radar (SAR) images using thresholding methods. The thresholding methods vary in complexity and number of required parameters. We proposed a simple thresholding method that takes advantage of the correlation between the river gauge and the flooding area. To show the applicability of the method, we used a 2014–2018 time series of 161 Sentinel 1 SAR images acquired over a wetland floodplain located in Northeast Poland. We validated the method by extracting local water line elevations from a high-resolution digital elevation model for three river gauges, which resulted in a root-mean-square error of 0.16 m, a bias of 0.07 m, and a correlation of 0.86 for the best scenario. The scenario analysis showed that the most important factor affecting the method's accuracy was a proper delineation of the zone in which the flooding extent area was calculated. This was because other water sources, uncorrelated with river flow, were present in the floodplain as open water. Additionally, higher accuracy was obtained for the VV than VH polarization. The discharge can be used instead of water elevations as a river gauge variable, but this results in more bias in the water extent estimates.

  • Flow distribution and heat transfer in minigap and minichannel heat exchangers during flow boiling
    • Michał Klugmann
    • Paweł Dąbrowski
    • Dariusz Mikielewicz
    2020 Pełny tekst APPLIED THERMAL ENGINEERING

    The topic of boiling heat transfer in miniscale geometries has focused the ever increasing interest of researchers in recent years. However, most of the works are related to mini- and microchannels and much less to minigaps. Meanwhile, minigaps allow for more comprehensive experimental studies, i.e. flow visualisations due to the flat, two-dimensional configuration of the flow. The results of the experimental investigations of a model plate heat exchanger, composed of a single plate with a heat exchange surface of 0.1 m × 0.2 m, made of brass are presented. The working fluid is pure ethanol. Between the plate and the cover of the exchanger, 0.5 mm and 1.0 mm thick minigaps are arranged. The 0.5 mm minigap has been compared to an equivalent minichannel structure (a set of 50 parallel minichannels) with an equal cross-sectional area (rectangular 1 mm × 1 mm). An attempt to intensify the heat exchange by modifying the minigap wall was made. Two variants were tested to check the potential increase in the heat transfer coefficient and flow resistance. The section cover is transparent in order to simultaneously register the flow structures with the measurements. The heat is supplied using a water circuit, where the temperature and flow of the water can be regulated in a constant temperature water tank. The flow configuration of the exchanger is countercurrent, with the vertical flow of ethanol from the bottom to the top. The inlet and outlet manifolds are arranged as trapezoidal (Z-type design). The authors have analysed the efficiency of heat transport and pressure drop depending on the system operating parameters. The visualisations are thoroughly analysed to better understand the process. The main advantages of the presented work are a direct comparison of minigap and minichannel structures while standardising all other parameters; an interesting application of a simple, passive heat transfer intensification method which resulted in the unification of the velocity fields in the minigap and reduced maldistribution.

  • Fluctuation-Enhanced Sensing
    • Graziella Scandurra
    • Janusz Smulko
    • Laszlo B. Kish
    2020 Journal of Sensors

    Fluctuation-enhanced sensing (FES) is an exciting and relatively new research field that promises to extend the range of information that can be extracted from a single sensor. In FES, the stochastic fluctuations of the sensor signal, rather than its average value, are recorded and analyzed. Typical components of such fluctuations are due to interactions at the microscopic level. Proper statistical analysis provides optimum sensory information.

  • Fluctuation-Enhanced Sensing (FES): A Promising Sensing Technique
    • Graziella Scandurra
    • Janusz Smulko
    • Laszlo Kish
    2020 Pełny tekst Applied Sciences-Basel

    Fluctuation-enhanced sensing (FES) is a very powerful odor and gas sensing technique and as such it can play a fundamental role in the control of environments and, therefore, in the protection of health. For this reason, we conduct a comprehensive survey on the state-of-the-art of the FES technique, highlighting potentials and limits. Particular attention is paid to the dedicated instrumentation necessary for the application of the FES technique and also in this case limits and possible future developments are highlighted. In particular, we address resolution, measurement speed, reproducibility, memory, noise, and other problems such as the influence of humidity. A number of techniques and guidelines are proposed to overcome these problems. Circuit solutions are also discussed.

  • FLUID BED COATING OF MINITABLETS AND PELLETS WITH OPTIMIZATION OF THE PROCESS BASED ON TAGUCHI METHOD
    • Turk Magdalena
    • Bożenna Kawalec-Pietrenko
    • Małgorzata Sznitowska
    • Piotr Rybarczyk
    2020 Pełny tekst Acta Poloniae Pharmaceutica - Drug Research

    Small particles like pellets are coated in fluid bed systems. This method can be also feasible for minitablets but the selection of optimal process parameters is complicated. The aim of the research was to optimize the coating process for minitablets and to compare the conditions required for pellets. Minimum fluidization velocities (umf) for 2.0 and 2.5 mm minitablets and 0.7-0.8 mm or 1.0-1.25 mm pellets were determined experimentally. Additionally, the results were verified using the Ergun equation. The smallest relative differences between the calculated and experimental values of umf were obtained for P0.7 (4.6%), while the largest for MT2.5 (11.8%). To simplify optimization of the coating process, Design of Experiment (DoE) based on the Taguchi method was employed. Selection of the best process parameters was based on the film thickness measurements for minitablets, while the sieve analysis was used for pellets to detect agglomeration. The best combination of process parameters resulted in uniform film thickness in minitablets, with RSD less than 15%, and the pellets batch containing only 0.25% of bonded particles. It was found that the largest impact on the uniform film deposition on minitablets had a spraying pressure, responsible for the size of coating mixture droplets. In the case of pellets, the most critical was the inlet air temperature. The presented research demonstrated that it was possible to achieve the best parameters of the coating process for minitablets and pellets by combining calculations of minimum fluidization velocity and Design of Experiment based on the Taguchi method.

  • Forecasting risks and challenges of digital innovations
    • Marcin Sikorski
    2020

    Forecasting and assessment of societal risks related to digital innovation systems and services is an urgent problem, because these solutions usually contain artificial intelligence algorithms which learn using data from the environment and modify their behaviour much beyond human control. Digital innovation solutions are increasingly deployed in transport, business and administrative domains, and therefore, if abused by a malicious human activity or by a technical malfunction, may pose serious threats to public and to society. Contrary to enthusiastic promotional messages from business and industry circles, the public is increasingly concerned by numerous examples of abuse of DIs, including hacking of specific digital solutions, misuse of social media for destructive activities, or digital addiction spreading among young users. Although certainly not a new concept, the issue of designers’ responsibility for the social impact of their creations is becoming ever more actual, as a well as the search for preventive technological, cultural and institutional measures.This chapter presents early results of testing a new approach to forecasting and prioritizing societal risks associated with deploying digital innovations. This approach – termed the RADI methodology – features two new elements: combining small expert panels with AHP-processed human assessments, and a relationship matrix visually mapping identified threats with available preventive policies, including the Socially Responsible Design approach. Although in an early version, the RADI methodology has been shown to be useful in guiding expert panels in profiling arrays of interventions to be undertaken by specific institutions against potential damage caused by non-validated and non-certified digital innovations.

  • Formaldehyde detection with chemical gas sensors based on WO3 nanowires decorated with metal nanoparticles under dark conditions and UV light irradiation
    • Benachir Bouchikhi
    • Tomasz Chludziński
    • Tarik Saidi
    • Janusz Smulko
    • Nezha El Bari
    • He Wen
    • Radu Ionescu
    2020 Pełny tekst SENSORS AND ACTUATORS B-CHEMICAL

    We report results of formaldehyde gas (CH2O) detection under dark conditions and UV light irradiation with pristine tungsten trioxide nanowires (WO3 NWs) and metal nanoparticles decorated WO3 NWs gas sensing layers. The resistive layers were deposited by one step aerosol assisted chemical vapor deposition (AACVD) on commercial alumina substrates with 10-pair interdigitated platinum electrodes. The elaborated gas sensors, based on pristine WO3 and on WO3 decorated with Au, Pt, Au/Pt, Ni and Fe nanoparticles, were investigated towards three concentrations of formaldehyde gas (5, 10 and 15 ppm) under dark conditions and under UV light irradiation at the wavelength of 394 nm. Two main effects were observed: firstly, under UV light irradiation the response time for CH2O desorption was significantly reduced with the exception of the nanomaterial with Fe NPs dopant; secondly, the gas induced baseline shift was reduced under UV light irradiation conditions. These results can be explained by the additional energy induced by the UV light, accelerating the adsorption-desorption processes. The results obtained confirmed that both the decoration of WO3 NWs with selected metal nanoparticles as well as sensors operation under UV light irradiation are a practical and affordable way to enhance gas sensing towards formaldehyde detection, although both strategies applied together did not introduce an amplified synergetic effect.

  • ─ Formation of a state institution on the basis of a process analysis - The concept of the institution of cadastre
    • Nogalski Bogdan
    • Adam Klimek
    • Joanna Czerska
    • Agnieszka Szpitte
    2020

    Modification of the structures of public administration encounters major obstacles. Institutional changes are difficult to introduce due to their complexity and broad impact. Non-substantial (political) factors are of importance as well. The resistance to change is aggravated by how difficult it is for decision-makers to assess the impact of the changes that are proposed. We present a method of handling such issues based on the process approach. It allows one to take a critical look at functioning state institutions and to develop draft changes. We discuss its application in the creation of concepts of institutional changes relying on the example of the administration segment, which handles geodesy and cartography in Poland. The study consists of three parts: the introduction, which defines the purpose of the work and presents the issues, method of conducting work, tools used, and the subject of research; the second part, in which the process of creating a cadastre concept is described based on the presented method; and the third part, namely the summary.