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Repozytorium publikacji
Politechniki Gdańskiej

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  • IoT for healthcare applications
    • Kamran Sayrafian
    • Sławomir Ambroziak
    • Dragana Bajic
    • Lazar Berbakov
    • Luis M. Correia
    • Krzysztof Cwalina
    • Concepcion Garcia-pardo
    • Gordana Gardašević
    • Konstantinos Katzis
    • Pawel Kulakowski
    • Kenan Turbic
    2021 Pełny tekst

    This chapter summarizes IRACON contributions related to the application of IoT in healthcare. It consists of the following three sections. Section 8.1 presents the measurement campaigns and the related statistical analysis to obtain various channel models for wearable and implantable devices. In addition, the importance of physical human-body phantoms used for channel, Specific Absorption Rate (SAR), and Electromagnetic (EM) exposure measurements are examined. Methodologies to improve the accuracy of these phantoms for various frequency bands are also discussed. Section 8.2 outlines methodologies to improve the medium access control (MAC) and networking layers of a body area networks along with possible architectures for remote health monitoring. Several applications such as localization, activity recognition, and crowdsensing and their corresponding technical challenges are also presented in this section. Finally, Section 8.3 introduces the concept of nanocommunications which can be considered as the nano-scale limit of the IoT technology spectrum. It provides an overview of the promising mechanisms that can establish data communication at molecular levels inside the human body as well as various interfacing techniques with macro-scale devices. It also highlights the revolutionary healthcare applications that could be enabled by this technology.

  • IoT protocols, architectures, and applications
    • Chiara Buratti
    • Erik G. Ström
    • Luca Feltrin
    • Laurent Clavier
    • Gordana Gardašević
    • Thomas Blazek
    • Lazar Berbakov
    • Titus Constantin Balan
    • Luis Orozco-Barbosa
    • Carles Anton-Haro
    • Piotr Rajchowski
    • Haibin Zhang
    2021

    The proliferation of embedded systems, wireless technologies, and Internet protocols have enabled the IoT to bridge the gap between the virtual and physical world enabling the monitoring and control of the environment by data processing systems. IoT refers to the inter-networking of everyday objects that are equipped with sensing, computation, and communication capabilities. These networks can collaboratively interact and perform a variety of tasks autonomously. A large variety of communication technologies has gradually emerged, reflecting a large diversity of application domains and requirements. This chapter describes some research activities performed with reference to such technologies and solutions. Section 7.1 reports the research in the framework of LPWANs, with emphasis on LoRa and Narrow Band IoT (NB-IoT) technologies. Studies on centralized approaches for IoT, mainly based on the IPv6 over the TSCH (6TiSCH) standard, are addressed in Section 7.2; while Section 7.3 deals with vehicular communications. Energy-efficient solutions are presented in section 7.4, being energy consumption one of the main issues of IoT; Section 7.5 reports some architectural solutions for the application of the SDN and NFV paradigms to IoT. The chapter ends with research on specific applications and drawing some conclusions. Most of the research described in the chapter has been conducted via experimentation, using testbeds described in IRACON White Paper on Experimental Facilities [AB18].

  • Ipertrofan Revisited—The Proposal of the Complete Stereochemistry of Mepartricin A and B
    • Paweł Szczeblewski
    • Witold Andrałojć
    • Justyna Polit
    • Aneta Żabka
    • Konrad Winnicki
    • Tomasz Laskowski
    2021 Pełny tekst MOLECULES

    Being a methyl ester of partricin, the mepartricin complex is the active substance of a drug called Ipertrofan (Tricandil), which was proven to be useful in treatment of benign prostatic hyperplasia and chronic nonbacterial prostatitis/chronic pelvic pain syndrome. Nevertheless, no direct structural evidence on the stereochemistry of its components has been presented to date. In this contribution, we have conducted detailed, NMR-driven stereochemical studies on mepartricins A and B, aided by molecular dynamics simulations. The absolute configuration of all the stereogenic centers of mepartricin A and B was defined as 3R, 7R, 9R, 11S, 13S, 15R, 17S, 18R, 19S, 21R, 36S, 37R, and 38S, and proposed as 41R. The geometry of the heptaenic chromophore of both compounds has been established as 22E, 24E, 26E, 28Z, 30Z, 32E, and 34E. Our studies on mepartricin ultimately proved that partricins A and B are structurally identical to the previously described main components of the aureofacin complex: gedamycin and vacidin, respectively. The knowledge of the stereochemistry of this drug is a fundamental matter not only in terms of studies on its molecular mode of action, but also for potential derivatization, aiming at improvement of its pharmacological properties.

  • Iron complexes with terminal and nonbridging phosphanido ligands
    • Kinga Kaniewska-Laskowska
    • Jerzy Pikies
    • Rafał Grubba
    2021 Pełny tekst INORGANICA CHIMICA ACTA

    This review discusses known iron complexes with terminal-bonded and nonbridging phosphanido ligands R2Pand their analogs, such as phosphanylphosphanido, borylphosphanido and oligophosphanido groups, that have been reported since 1960s. Particular attention is focused on the synthesis and structural features of these complexes, which have a direct impact on their philicity and further reactivity. Moreover, their application in catalysis and materials science will be described.

  • Is Digital Government Advancing Sustainable Governance? A Study of OECD/EU Countries
    • Jaromir Durkiewicz
    • Tomasz Janowski
    2021 Pełny tekst Sustainability

    International bodies and numerous authors advocate a key role for Digital Government (DG) in improving public governance and achieving other policy outcomes. Today, a particularly relevant outcome is advancing Sustainable Governance (SG), i.e., the capacity to steer and coordinate public action towards sustainable development. This article performs an empirical study of the relationship between DG and SG using data about 41 OECD/EU countries from the United Nations’ E-Government Survey and the Bertelsmann’s Sustainable Governance Indicators project, covering the period from 2014 to 2020. We examine if DG progress pairs with SG progress, apply a DEA model to find out which countries are efficient in using DG for better SG, and uncover cases of imbalance where high DG pairs with poor SG and vice versa. The results show that the efficiency in using DG for SG strongly varies, and that some DG leaders persistently fail to advance or even regress their SG. These findings refute the claims about the benign role of DG and points at democracy as the “weak link” in the analyzed relation.

  • Is the microfiltration process suitable as a method of removing suspended solids from rainwater?
    • Karolina Fitobór
    • Bernard Quant
    2021 Pełny tekst Resources-Basel

    Due to climate change and anthropogenic pressure, freshwater availability is declining in areas where it has not been noticeable so far. As a result, the demands for alternative sources of safe drinking water and effective methods of purification are growing. A solution worth considering is the treatment of rainwater by microfiltration. This study presents the results of selected analyses of rainwater runoff, collected from the roof surface of individual households equipped with the rainwater harvesting system. The method of rainwater management and research location (rural area) influenced the low content of suspended substances (TSS < 0.02 mg/L) and turbidity (< 4 NTU). Microfiltration allowed for the further removal of suspension particles with sizes larger than 0.45 μm and with efficiency greater than 60%. Granulometric analysis indicated that physical properties of suspended particles vary with the season and weather. During spring, particles with an average size of 500 μm predominated, while in autumn particles were much smaller (10 μm). However, Silt Density Index measurements confirmed that even a small amount of suspended solids can contribute to the fouling of membranes (SDI > 5). Therefore, rainwater cannot be purified by microfiltration without an appropriate pretreatment.

  • Is This Distance Teaching Planning That Bad?
    • Izabela Mironowicz
    • Martina Schretzenmayr
    2021 Pełny tekst disP

    In spring 2020, university courses were moved into the virtual space due to the Covid-19 lockdown. In this paper, we use experience from courses at Gdańsk University of Technology and ETH Zurich to identify core problems in distance teaching planning and to discuss what to do and what not to do in teaching planning after the pandemic. We conclude that we will not return to the state of (teaching) affairs that we had previously. The availability of recordings of lectures and videos, de-localisation of both students and teachers, the experience of spatio-temporal autonomy will lead to new forms of teaching as both students and teachers experienced some aspects of remote teaching even more efficient than real-world teaching. On the other hand, remote teaching of elements of learning that required interaction, e.g. group and studio work, brainstorming, discussion to foster critical thinking, cannot replace the real experience of the classroom.

  • Isocyanate-Free Polyurethanes
    • Marcin Włoch
    • Kamila Rohde
    2021

    Isocyanate-free polyurethanes (also called non-isocyanate polyurethanes, or NIPUs) are alternatives to the conventional (commercially used) polyurethanes synthesized using di- or polyisocyanates, polyols, and chain extenders with low molecular weight. The major routes of NIPUs’ synthesis involve polyaddition of cyclic carbonates and di- or polyamines, polycondensation of carbamates, and diols. The most important intermediates are compounds containing five-membered cyclic carbonate groups, which can be obtained by cycloaddition of carbon dioxide to epoxy compounds. Starting molecules for the synthesis of NIPUs can be petroleum based (e.g., diols with low molecular weight or polyols) or biobased (e.g., vegetable oils, limonene, sugars, or lignin). This chapter covers the synthesis and properties of five-membered cyclic carbonate intermediates, along with the polyurethanes obtained using them. In the case of cyclic carbonate intermediates, special attention is paid to cycloaddition of carbon dioxide to di- or polyfunctional glycidyl ethers.

  • Isogeometric Shell FE Analysis of the Human Abdominal Wall
    • Bartosz Borzeszkowski
    • Thang X. Duong
    • Roger A. Sauer
    • Izabela Lubowiecka
    2021

    In this paper a nonlinear isogeometric Kirchhoff-Love shell model of the human abdominal wall is proposed. Its geometry is based on in vivo measurements obtained from a polygon mesh that is transformed into a NURBS surface, and then used directly for the finite element analysis. The passive response of the abdominal wall model under uniform pressure is considered. A hyperelastic membrane model based on the Gasser-Ogden-Holzapfel tissue model is used together with the Koiter bending model to describe the material behavior. Due to the mixed material formulation, different sets of constitutive parameters are examined, such that the influence of each term is analyzed. The membrane contribution of the material model shows a major impact on the displacement magnitude and reflects more reliably the nonlinear character of the deformation.

  • Isolation Number versus Domination Number of Trees
    • Magdalena Lemańska
    • Maria Jose Souto-Salorio
    • Adriana Dapena
    • Francisco Vazquez-Araujo
    2021 Pełny tekst Mathematics

    If G=(VG,EG) is a graph of order n, we call S⊆VG an isolating set if the graph induced by VG−NG[S] contains no edges. The minimum cardinality of an isolating set of G is called the isolation number of G, and it is denoted by ι(G). It is known that ι(G)≤n3 and the bound is sharp. A subset S⊆VG is called dominating in G if NG[S]=VG. The minimum cardinality of a dominating set of G is the domination number, and it is denoted by γ(G). In this paper, we analyze a family of trees T where ι(T)=γ(T), and we prove that ι(T)=n3 implies ι(T)=γ(T). Moreover, we give different equivalent characterizations of such graphs and we propose simple algorithms to build these trees from the connections of stars.

  • Iso-Partricin, an Aromatic Analogue of Amphotericin B: How Shining Light on Old Drugs Might Help Create New Ones
    • Paweł Szczeblewski
    • Justyna Górska
    • Witold Andrałojć
    • Patryk Janke
    • Karolina Wąsik
    • Tomasz Laskowski
    2021 Pełny tekst Antibiotics-Basel

    Partricin is a heptaene macrolide antibiotic complex that exhibits exceptional antifungal activity, yet poor selective toxicity, in the pathogen/host system. It consists of two compounds, namely partricin A and B, and both of these molecules incorporate two cis-type bonds within their heptaenic chromophores: 28Z and 30Z. In this contribution, we have proven that partricins are susceptible to a chromophore-straightening photoisomerization process. The occurring 28Z→28E and 30Z→30E switches are irreversible in given conditions, and they are the only structural changes observed during the experiment. The obtained all-trans partricin’s derivatives, namely iso-partricins A and B, exhibit very promising features, potentially resulting in the improvement of their selective toxicity.

  • Isothermal Calorimetry and Compressive Strength Tests of Mortar Specimens for Determination of Apparent Activation Energy
    • Aleksandra Kuryłowicz-Cudowska
    • Elżbieta Haustein
    2021 Pełny tekst JOURNAL OF MATERIALS IN CIVIL ENGINEERING

    The hydration process of cementitious materials involves a thermally activated reaction that depends on the composition of the mixture and the curing temperature. The main parameter affecting the temperature variation of cast-in-place concrete is the apparent activation energy, which can be used for the efficient prediction of the temperature evolution and maturity index of hardening concrete. This paper discusses two methods to determine the activation energy of mortar specimens, whose mixture proportions are based on standards. The first approach is based on isothermal calorimetry measurements, and the second involves compression tests of mortar samples stored under four different temperature conditions. Mortar mixtures with ordinary portland cement and two rates of cement substitution with siliceous fly ash (10% and 20%) are investigated. The values of the activation energy obtained using the two approaches are compared. Finally, the effectiveness of different tests in determining the activation energy, and thus, maturity index is highlighted.

  • Isothermal Vulcanization and Non-Isothermal Degradation Kinetics of XNBR/Epoxy/XNBR-g-Halloysite Nanotubes (HNT) Nanocomposites
    • Seyed Paran
    • Ghasem Naderi
    • Elnaz Movahedifar
    • Maryam Jouyandeh
    • Krzysztof Formela
    • Xavier Colom
    • Javier Cañavate
    • Mohammad Saeb
    2021 Pełny tekst Materials

    The effect of several concentrations of carboxylated nitrile butadiene rubber (XNBR) functionalized halloysite nanotubes (XHNTs) on the vulcanization and degradation kinetics of XNBR/epoxy compounds were evaluated using experimental and theoretical methods. The isothermal vulcanization kinetics were studied at various temperatures by rheometry and differential scanning calorimetry (DSC). The results obtained indicated that the nth order model could not accurately predict the curing performance. However, the autocatalytic approach can be used to estimate the vulcanization reaction mechanism of XNBR/epoxy/XHNTs nanocomposites. The kinetic parameters related to the degradation of XNBR/epoxy/XHNTs nanocomposites were also assessed using thermogravimetric analysis (TGA). TGA measurements suggested that the grafted nanotubes strongly enhanced the thermal stability of the nanocomposite.

  • Iterative Global Sensitivity Analysis Algorithm with Neural Network Surrogate Modeling
    • Yen-Chen Liu
    • Jethro Nagawkar
    • Leifur Leifsson
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2021

    Global sensitivity analysis (GSA) is a method to quantify the effect of the input parameters on outputs of physics-based systems. Performing GSA can be challenging due to the combined effect of the high computational cost of each individual physics-based model, a large number of input parameters, and the need to perform repetitive model evaluations. To reduce this cost, neural networks (NNs) are used to replace the expensive physics-based model in this work. This introduces the additional challenge of finding the minimum number of training data samples required to train the NNs accurately. In this work, a new method is introduced to accurately quantify the GSA values by iterating over both the number of samples required to train the NNs, terminated using an outer-loop sensitivity convergence criteria, and the number of model responses required to calculate the GSA, terminated with an inner-loop sensitivity convergence criteria. The iterative surrogate-based GSA guarantees converged values for the Sobol’ indices and, at the same time, alleviates the specification of arbitrary accuracy metrics for the surrogate model. The proposed method is demonstrated in two cases, namely, an eight-variable borehole function and a three-variable nondestructive testing (NDT) case. For the borehole function, both the first- and total-order Sobol’ indices required 200 and 10 5 105 data points to terminate on the outer- and inner-loop sensitivity convergence criteria, respectively. For the NDT case, these values were 100 for both first- and total-order indices for the outer-loop sensitivity convergence, and 10 6 106 and 10 3 103 for the inner-loop sensitivity convergence, respectively, for the first- and total-order indices, on the inner-loop sensitivity convergence. The differences of the proposed method with GSA on the true functions are less than 3% in the analytical case and less than 10% in the physics-based case (where the large error comes from small Sobol’ indices).

  • Jak wykraść złoto smokowi? - uczenie ze wzmocnieniem w świecie Wumpusa
    • Karol Draszawka
    2021

    Niniejszy rozdział zawiera łagodne wprowadzenie do problematyki uczenia ze wzmocnieniem, w którym podstawy teoretyczne wyjaśniane są na przykładzie przewodnim, jakim jest zagadnienie nauczenia agenta poruszania się w świecie potwora o imieniu Wumpus (ang. Wumpus world), klasycznym środowisku do testowania logicznego rozumowania agentów (problem nietrywialny dla algorytmów uczenia ze wzmocnieniem). Przedstawiona jest główna idea uczenia ze wzmocnieniem. Wprowadzono formalizację wieloetapowych procesów decyzyjnych w oparciu o model Procesu Decyzyjnego Markowa, zaznaczono dylemat eksploracja - eksploatacja, przestawiono klasyczny algorytm Q-learning, a także jego wariant głęboki, tj. algorytm DQN, jako przedstawiciela dziedziny głębokiego uczenia ze wzmocnieniem. Zaznaczono problemy częściowej obserwacji stanu oraz rzadko występującej nagrody, jak i sposoby poradzenia sobie z nimi, w tym: kumulacja wiedzy o stanie na podstawie częściowych obserwacji, kształtowanie funkcji nagrody, tzw. curriculum learning oraz innowacyjną podwójną strategię eps-zachłanną.

  • Jaka przestrzeń dla rozwoju lokalności?
    • Gabriela Rembarz
    2021

    Podwórko-osiedle-dzielnica: wokół tej osi koncentruje się dziś dyskusja publiczna nad lokalnością i rozwojem miejskiej wspólnotowości. Te trzy elementy są zarazem najważniejszymi skalami budowania przestrzeni zamieszkania, od której zależy, czy mieszkamy "razem", czy jedynie obok siebie. Czy wysoka jakość miejskiej przestrzeni powinna być przez nas traktowana bardziej jako luksus, czy przeciwnie - jako dobro pierwszej potrzeby? Dlaczego budowa lokalnej wspólnotowości wymaga kameralności i mozaikowości? Jak projektować dzielnice, w których dobrze będzie się żyło zarówno ośmio-, jak i osiemdziesięciolatkom?Odpowiedzi na te pytania służą w publikacji do nakreślenia pola problemowego związanego ze znaczeniem formy przestrzennej dla budowania jakości dobrego sąsiedztwa współodpowiedzialnego za budowanie lokalności i odporności wspólnoty miejskiej.

  • Jakość oprogramowania w zwinnym podejściu do zarządzania projektami informatycznymi
    • Kamil Brodnicki
    2021 Problemy Jakości

    Cel: Celem artykułu jest ocena, czy wykorzystanie podejścia zwinnego Scrum w organizacji podnosi jakość wytwarzanego oprogramowania oraz próba uzyskania odpowiedzi na pytanie, jak nowelizacja Przewodnika po Scrumie (Scrum Guide) z listopada 2020 roku wpłynęła na proces wytwarzania oprogramowania. Projekt badania/metodyka badawcza/koncepcja: Przyjętą metodyką badawczą jest przegląd literatury przedmiotu oraz badania własne autora. Wyniki/wnioski: Wnioskiem z przeprowadzonych badań jest fakt, że zastosowanie podejścia zwinnego Scrum pozytywnie wpływa na jakość wytwarzanego oprogramowania. Postępowanie zgodnie z wytycznymi zawartymi w Przewodniku oraz podnoszenie kompetencji w zespołach wytwórczych powoduje, że wzrasta świadomość dotycząca wytwarzanych produktów, co ma bezpośredni wpływ na jakość. Ograniczenia: Do ograniczeń w prowadzonych badaniach zaliczyć można stosunkowo niewielką liczbę przeprowadzonych wywiadów. Liczba ta wynika z trudności w uzyskaniu obecnie rzetelnych danych, ale zdaniem autora badania takie są znacznie bardziej wiarygodne i niosą większą wartość poznawczą aniżeli badania ilościowe. Zastosowanie praktyczne: Uzyskane wyniki niewątpliwie przyczynią się do poprawy obszarów w organizacji i ciągłego ich doskonalenia, a organizacjom zamierzającym dokonać transformacji z podejścia klasycznego do zwinnego – uniknąć powielania potencjalnych błędów. Oryginalność/wartość poznawcza: Dotychczas w literaturze przedmiotu brak jest badań skupiających się na porównaniu bieżącej wersji Przewodnika po Scrumie z jego poprzednią wersją i wpływu tychże różnic na funkcjonowanie organizacji.

  • Jakość w pomorskim - Biznes i uczelnia w dążeniu do jakości/ Nowy Model EFQM
    • Anna Wendt
    2021 Pełny tekst Biuletyn Informacyjny PR FSNT NOT w Gdańsku

    W dniu 8.10.2021 na Wydziale Zarządzania i Ekonomii Politechniki Gdańskiej odbyła się konferencja pt. „Biznes i uczelnia w dążeniu do jakości”. Organizatorami wydarzenia była Katedra Inżynierii Zarządzania i Jakości Wydziału Zarządzania i Ekonomii Politechniki Gdańskiej (PG), firma Flex oraz Fundacja Edukacyjne Centrum Doskonalenia (ECD). Celem spotkania była wymiana poglądów i doświadczeń oraz określenie kierunków współpracy biznesu i uczelni w ramach działań projakościowych. Podczas konferencji poruszono temat modelu EFQM (Prof. Dr hab. Arkadiusz Wierzbic) oraz Pomorskiej Nagrody Jakości (Paulina Orłowska - NOT w Gdańsku). Model EFQM jest rozpoznawalnym na całym świecie narzędziem wspierającym organizacje w ich zarządzaniu i doskonaleniu wyników. Model buduje podstawy do osiągania długoterminowego sukcesu oraz zrównoważonego rozwoju organizacji. Model EFQM co jakiś czas jest doskonalony, tak by zapewnić jego adekwatność do potrzeb organizacji.

  • Jedno- i wielordzeniowe heteroleptyczne silanotiolany Co(II) i Ni(II) - badania strukturalne, spektroskopowe i magnetyczne
    • Daria Kowalkowska-Zedler
    2021 Pełny tekst

    Doniesienia literaturowe wskazują na możliwość zastosowania związków kompleksowych Co(II) i Ni(II) jako jednocząsteczkowe magnesy molekularne (SMM). Wysiłki naukowców skupiają się na poznaniu zależności pomiędzy strukturą molekularną związków, a ich właściwościami magnetycznymi. Znane są przykłady związków typu SMM opartych na jonach Co(II) i Ni(II), w których metal koordynowany jest przez miękkie S-donorowe ligandy tiolanowe, jednak obszar ten nie został jeszcze wystarczająco poznany. W ramach tej pracy otrzymano szereg heteroleptycznych związków kompleksowych Co(II) i Ni(II), w których rolę miękkiego liganda S-donorowego pełni tri-tert-butoksysilanotiol, natomiast zastosowane ligandy N-donorowe to związki będące aminami cyklicznymi, pochodnymi imidazolu lub pirydyny. Otrzymano kryształy jednordzeniowych związków 1-3. 6, 8, 9-13, dwurdzeniowych kompleksów 4 i 7 oraz polimerów koordynacyjnych 14 i 15, dla których wykonano pomiary XRD. Wszystkie związki zostały scharakteryzowano za pomocą spektroskopii FT-IR, a dla związków 1-8 oraz 15 dodatkowo wykonano stało- i zmiennoprądowe pomiary magnetyczne oraz spektroskopii EPR w paśmie X. Związki 1-8 wykazują zachowanie typowe dla paramagnetycznych jonów Co(II) w stanie wysokospinowym, ze znacznym wpływem efektu ZFS w niskich temperaturach. W związku 15 ujawniono obecność słabych oddziaływań Ni···Ni typu AFM.

  • Joints Of Steel Sandwich Structures
    • Janusz Kozak
    2021 Pełny tekst Polish Maritime Research

    Steel sandwich structures are perceived as alternatives to single-skin welded structures in the shipbuilding industry due its advantages like significant reduction of mass in relation to typical single skin structure. However, beside problems with their strength properties itself, applications in real structures requires of solving the problem of joining, both for connection sandwich to sandwich as well as sandwiches to single-shell structures. Proper design of joints is connected with some factors like lack of attempt to interior of panel, introduction of additional parts and welds with completely different stiffness. In the paper the results of laboratory fatigue tests of selected joints as well as numerical calculation of stresses for different kind of joints of sandwich structures are presented. As result of calculations optimisation of geometry for selected joints is performed.

  • Józef Kostro – absolwent Politechniki Gdańskiej zamordowany w obozie koncentracyjnym w Auschwitz
    • Witold Parteka
    2021 Pismo PG

    Artykuł przedstawia sylwetkę Józefa Kostro. W październiku 2020 roku do zbiorów Sekcji Historycznej PG przekazano materiały dotyczące inżyniera dyplomowanego Józefa Kostro – studenta przedwojennej Politechniki Gdańskiej (Technische Hochschule der Freien Stadt Danzig) i absolwenta Wydziału Budowy Maszyn z 1930 roku. Ofiarodawcą jest prof. Ludwik Kostro – syn, emerytowany profesor Uniwersytetu Gdańskiego, filozof, fizyk, biblista, wykładowca gdańskich uczelni. Materiał dokumentacyjny jest różnorodny i bardzo wartościowy.

  • Jubileusz 75-lecia powstania Politechniki Gdańskiej analiza publikacji pracowników Politechniki Gdańskiej (1945–2019)
    • Beata Adamczak
    • Anna Wałek
    2021 Pełny tekst Pismo PG

    W niniejszym artykule zaprezentowano szczegółową analizę bibliometryczną publikacji pracowników Politechniki Gdańskiej w latach 1945–2019.

  • Jubileusz Stowarzyszenia Inżynierów i Techników Polskich "Polonia Technica"
    • Adam Barylski
    2021 Pismo PG

    Przedstawiono przebieg uroczystości 80 lecia działalności Stowarzyszenia Inżynierów i Techników Polskich "Polonia Technica" w USA. Obchody rocznicowe odbyły się 23 maja 20121 roku w Nowym Jorku. Założycielem Stowarzyszenia był Walery Starczewski, absolwent Politechniki Gdańskiej z roku 1926.

  • Jumping Wave Characteristic during Low Plasticity Burnishing Process
    • Stefan Dzionk
    • Michał Dobrzyński
    • Bogdan Ścibiorski
    2021 Pełny tekst Materials

    During the low plasticity burnishing process of soft materials such as carbon steel with a hardness of up to 40 HRC (Rockwell grade) a raised structure of the material known as the Jumping Wave forms in front of the tool roll. This phenomenon significantly disturbs the burnishing process, but is very poorly described in the literature. This article presents studies of this phenomenon on the example of burnished 1.0562 steel. The research concerns the changes in the surface structure of the processed material as well as changes in the structure of the material during this process. The research shows changes in the geometric structure of the surface made in the 3D system and their parametric description. Moreover, the work presents an analysis of the metallographic structure in the tool zone. The research showed occurrence of material slippages in the wave in front of the tool, which creates an additional structure on the surface. These tests make it possible to better understand the process of changes that take place in the surface layer of the processed element in the low plasticity burnishing process.

  • Just look at to open it up: A biometric verification facility for password autofill to protect electronic documents
    • Maciej Smiatacz
    • Bogdan Wiszniewski
    2021 Pełny tekst MULTIMEDIA TOOLS AND APPLICATIONS

    Electronic documents constitute specific units of information, and protecting them against unauthorized access is a challenging task. This is because a password protected document may be stolen from its host computer or intercepted while on transfer and exposed to unlimited offline attacks. The key issue is, therefore, making document passwords hard to crack. We propose to augment a common text password authentication interface to encrypted documents with a biometric facial identity verification providing highly personalized security mechanism based on pseudo-identities. In consequence the encrypted document can be unlocked with the legitimate user’s face, while for everyone else stays encrypted with a hard to crack text password. This paper makes two contributions: (1) The proposed scheme enables password autofill without referring to any external service, which significantly limits the possibilities of an attack by adversaries when opening, reading and editing the protected document, (2) By the adoption of biometric verification techniques enabling fine-tuning of false acceptance and false rejection rates, it provides for responsible adaptation to users.

  • Justifying the prolongation of the service life of the bearing structure of a tank car when using Y25 bogies
    • Oleksij Fomin
    • Alyona Lovska
    • Kseniia Ivanchenko
    • Ievgen Medvediev
    2021 Pełny tekst Eastern-European Journal of Enterprise Technologies [ Восточно-Европейский журнал передовых технологий ]

    This paper substantiates the use of Y25 bogies under tank cars in order to prolong their service life. The reported study has been carried out for a tank car with rated parameters, as well as the actual ones, registered during full-scale research. Mathematical modeling was performed to determine the basic indicators of the tank car dynamics. The differential equations of motion were solved by a Runge-Kutta method using the Mathcad software package (USA). It was established that the use of Y25 bogies under a tank car with rated parameters could reduce the acceleration of its bearing structure by almost 39 % compared to the use of standard 18-100 bogies. Applying the Y25 bogies under a tank car with the actual parameters reduces the acceleration of its load-bearing structure by almost 50 % compared to the use of standard 18‒100 bogies. The derived acceleration values were taken into performed using the SolidWorks Simulation software (France). The resulting stress values are 18 % lower than the stresses acting on the load-bearing structure of a tank car equipped with 18-100 bogies. For the load-bearing structure of a tank car with the actual parameters, the maximum equivalent stresses are 16 % lower than the stresses when the 18‒bogies are used. The design service life of the load-bearing structure of a tank car was estimated taking into consideration the use of Y25 bogies. The calculations showed that the design service life of the bearing structure of a tank car equipped with Y25 bogies is more than twice as high as that obtained for 18-100 bogies. The study reported here would contribute to compiling recommendations for prolonging the service life of the load-bearing structures of tank cars

  • KAMIŃSKI W.: Modelowanie przemieszczeń pionowych mieszaną, ortogonalną metodą najmniejszych kwadratów (Mixed Total Least Squares)
    • Waldemar Kamiński
    2021 Inżynieria Morska i Geotechnika

    Problematyka modelowania przemieszczeń pionowych standardową metodą najmniejszych kwadratów i mieszaną ortogonalną metodą najmniejszych kwadratów. Przykłady praktycznych obliczeń na rzeczywistych i symulowanych wynikach obserwacji.

  • Keystroke Dynamics Patterns While Writing Positive and Negative Opinions
    • Agata Kołakowska
    • Agnieszka Landowska
    2021 Pełny tekst SENSORS

    This paper deals with analysis of behavioural patterns in human–computer interaction. In the study, keystroke dynamics were analysed while participants were writing positive and negative opinions. A semi-experiment with 50 participants was performed. The participants were asked to recall the most negative and positive learning experiences (subject and teacher) and write an opinion about it. Keystroke dynamics were captured and over 50 diverse features were calculated and checked against the ability to differentiate positive and negative opinions. Moreover, classification of opinions was performed providing accuracy slightly above the random guess level. The second classification approach used self-report labels of pleasure and arousal and showed more accurate results. The study confirmed that it was possible to recognize positive and negative opinions from the keystroke patterns with accuracy above the random guess; however, combination with other modalities might produce more accurate results.

  • Kinetic analysis of the reduction of a ternary system of Bi, Sb and Te oxides by hydrogen for BiSbTe3 synthesis
    • Bartosz Trawiński
    • Bogusław Kusz
    2021 Pełny tekst THERMOCHIMICA ACTA

    Reduction in a hydrogen atmosphere of Bi2O3, Sb2O3 and TeO2 mixes oxides for the synthesis of BiSbTe3 was analysed. The reduction reactions of Sb2O3 and Sb2O4 oxides, as well as Bi2O3+Sb2O3 and Sb2O3+3TeO2 mix- tures, were also evaluated. The reduction of Sb2O4 is investigated for the first time. The reactions of the mixed oxides systems also were not the subject of research so far despite being used for synthesis of the (Bi,Sb)2Te3 material. The study comprised of kinetic analysis of TGA curves performed with non-parametric and iso- conversional methods. Insight into powders’ structure during the process was taken to identify processes taking place. The results show, that Sb2O3 present in the reduced oxidizes to Sb2O4. This redox process between Sb oxide and another oxide takes place directly. The self-heating effect caused by elemental tellurium is diminished in the presence of Bi, because Bi-Te phases decrease the content of the elemental Te.

  • Kinetics of the Organic Compounds and Ammonium Nitrogen Electrochemical Oxidation in Landfill Leachates at Boron-Doped Diamond Anodes
    • Barbara Wilk
    • Małgorzata Szopińska
    • Aneta Łuczkiewicz
    • Michał Sobaszek
    • Ewa Siedlecka
    • Sylwia Fudala-Książek
    2021 Pełny tekst Materials

    Electrochemical oxidation (EO) of organic compounds and ammonium in the complex matrix of landfill leachates (LLs) was investigated using three different boron-doped diamond electrodes produced on silicon substrate (BDD/Si)(levels of boron doping [B]/[C] = 500, 10,000, and 15,000 ppm—0.5 k; 10 k, and 15 k, respectively) during 8-h tests. The LLs were collected from an old landfill in the Pomerania region (Northern Poland) and were characterized by a high concentration of N-NH4+ (2069 ± 103 mg·L−1), chemical oxygen demand (COD) (3608 ± 123 mg·L−1), high salinity (2690 ± 70 mg Cl−·L−1, 1353 ± 70 mg SO42−·L−1), and poor biodegradability. The experiments revealed that electrochemical oxidation of LLs using BDD 0.5 k and current density (j) = 100 mA·cm−2 was the most effective amongst those tested (C8h/C0: COD = 0.09 ± 0.14 mg·L−1, N-NH4+ = 0.39 ± 0.05 mg·L−1). COD removal fits the model of pseudo-first-order reactions and N-NH4+ removal in most cases follows second-order kinetics. The double increase in biodegradability index—to 0.22 ± 0.05 (BDD 0.5 k, j = 50 mA·cm−2) shows the potential application of EO prior biological treatment. Despite EO still being an energy consuming process, optimum conditions (COD removal > 70%) might be achieved after 4 h of treatment with an energy consumption of 200 kW·m−3 (BDD 0.5 k, j = 100 mA·cm−2).

  • Klasyfikacja aktywności kory wzrokowej za pomocą elektroencefalografu
    • Jakub Atroszko
    2021

    W niniejszej pracy została przedstawiona metodologia konstrukcji i oceny systemu cyfrowego automatycznie klasyfikującego dane pochodzące z elektroencefalografu. Opracowana procedura badawcza pozwoliła na przetestowanie rozwiązania na różnych osobach, w różnym wieku, o różnych porach dnia, z wykorzystaniem różnych konfiguracji urządzeń i modeli zjawiska. Uzyskano stuprocentową skuteczność automatycznego rozpoznania stanu spoczynkowego kory wzrokowej. Architektura rozwiązania została oparta o algorytm maszyny wektorów nośnych, a także wektorowe reprezentacje aktywności mózgu utworzone z wykorzystaniem szybkiej transformacji Fouriera.

  • KLASYFIKACJA EMOCJI W MUZYCE FILMOWEJ Z WYKORZYSTANIEM TESTÓW SUBIEKTYWNYCH
    • Tomasz Ciborowski
    • Szymon Reginis
    • Adam Kurowski
    • Dawid Weber
    • Bożena Kostek
    2021 Pełny tekst

    Celem referatu było przedstawienie testów odsłuchowych, w których zadaniem osób ankietowanych było przypisanie danego fragmentu muzycznego do odpowiedniej klasy emocji. Kolejne kroki eksperymentu obejmowały wybór muzyki filmowej do testów (baza Epidemic Sound), przygotowanie założeń ankiety oraz modelu emocji wykorzystywanych w testach odsłuchowych, jak również konstrukcj ˛e ankiety. Ankieta została zrealizowana za pomoc ˛a formularzy Google. W ramach analizy wyników testów odsłuchowych w pierwszej kolejności sprawdzone zostały korelacje pomi ˛edzy parami klas emocji przypisanych do katalogów utworów w bazie Epidemic Sound. Nast ˛epnie zmapowano uzyskane wyniki ankiety na wykorzystany model, który zawiera emocje odniesienia (autorski model). W referacie zawarte też zostały histogramy zawieraj ˛ace przykłady list rankingowych przypisań kolorów do emocji. Przedstawiony również został zarys dalszych eksperymentów.

  • KLASYFIKACJA STANU TECHNICZNEGO UKŁADU WTRYSKOWEGO SILNIKA Z ZAPŁONEM SAMOCZYNNYM NA PODSTAWIE POMIARU SKŁADU SPALIN
    • Jacek Rudnicki
    • Jakub Bujczenko
    2021 Pełny tekst Journal of Polish CIMEEAC

    Artykuł przedstawia wyniki empirycznej weryfikacji hipotezy pozwalającej na opracowanie sprzętowo – programowego klasyfikatora stanu technicznego układu wtryskowego silnika z zapłonem samoczynnym. Pozytywna weryfikacja wspomnianej hipotezy, która wiąże przebieg procesu spalania, skład chemiczny spalin oraz wybrane stany niesprawności technicznej układu wtryskowego pozwoliła na przedstawienie koncepcji klasyfikatora w rozpatrywanym zbiorze klas stanu układu wtryskowego.

  • Klasyfikacja tekstu przy użyciu grafowych sieci neuronowych
    • Robert Benke
    2021

    Współczesnym algorytmom analizy tekstu wciąż daleko do ludzkiego poziomu jego zrozumienia. Jednym z wyzwań jest znajdowanie przez maszynę związków pomiędzy odległymi fragmentami tekstu. Próbą rozwiązania tego problemu są grafowe reprezentacje tekstu, które bardzo dobrze sprawdzają się w przedstawianiu złożonych zależności. W tekście opisane zostały dwie metody grafowej reprezentacji tekstu oraz algorytm grafowych konwolucyjnych sieci neuronowych.

  • Klasyfikator Adaboost w detekcji i rozpoznawaniu obiektów graficznych
    • Jerzy Dembski
    2021

    W pracy opisano metode Adaboost w zastosowaniu do detekcji obiektów graficznych, takich jak twarze lub rozpoznawania np. osób na podstawie obrazu twarzy. Przedstawiono podstawy algorytm, wersje kaskadowa, schemat przepływu danych i sterowania w zadaniu detekcji twarzy oraz sposoby adaptacji tej metody do problemów wieloklasowych. Opisano równiez zbiory cech obrazów, takie jak HAAR, LBP czy HOG stosowane w zadaniach detekcji i rozpoznawania obiektów graficznych.

  • Knowledge risks in organizations – Insights from companies
    • Małgorzata Zięba
    • Susanne Durst
    • Martyna Gonsiorowska
    • Zeynaddin Zralov
    2021 Pełny tekst

    Purpose: Knowledge risks are increasingly becoming a great challenge to a variety of organizations. At the same time, academic research on such types of risks, their consequences, and potential ways of overcoming them is still scarce and fragmented. To fill this gap, the paper aims to find out do companies manage their knowledge risks, what are the possible knowledge risks they face and have they observed an increase of knowledge risks during the COVID-19 pandemic. The paper is aimed to present insights on different types of knowledge risks that organizations face, and the ways organizations handle them. The paper also proposes some potential countermeasures organizations might use to mitigate the consequences of knowledge risks. Methodology: The study presents the results of a quantitative survey performed among 60 professionals dealing with management and knowledge risks in organizations. In the study, the authors also have examined what tools and methods are used to manage these risks. The study also explores the level of readiness organizations have to address potential knowledge risks. Findings: The theoretical study has allowed us to identify a variety of knowledge risks, which can bear severe consequences for organizations, such as knowledge loss, knowledge leaking, knowledge hiding, or risks related to cybercrime. All these risks may potentially reduce the productivity in organizations, thus leading to the degradation of organizational performance. Research limitations: Research results are limited to the convenience sample that was selected for the study and thus may not give a comprehensive overview of the state of the art. Practical implications: The study provides useful insights for managers and owners of organizations in need of dealing with the knowledge risks in their organizations. The paper is enriched with a number of sample solutions that they may apply for the sake of their organization. Originality/value: The paper lays the ground for a better understanding of the knowledge risks that organizations need to face nowadays. As such, the paper offers food for thought for researchers dealing with the topic of knowledge risks, knowledge management, and organizational risk management in general.

  • Knowledge Risks in the COVID-19 Pandemic
    • Małgorzata Zięba
    • Susanne Durst
    • Martyna Gonsiorowska
    2021 Pełny tekst

    This conceptual paper aims to identify, present, and analyse potential knowledge risks organizations face in external and dynamic crises such as the COVID-19 pandemic. Until only recently, many researchers and practitioners have perceived knowledge primarily as something positive. This view has changed recently with a growing number of studies highlighting risks related to knowledge. The on-going COVID-19 pandemic can be seen as an additional triggering point which has brought several new knowledge risks. Research on knowledge risks, their consequences and potential ways of handling them is still only in its beginning and consequently rather fragmented. To address this situation, this paper is aimed to provide some theoretical insights into knowledge risks and their possible implications organizations are exposed to in an external and dynamic crisis such as the COVID-19 crisis. To reach this aim, this paper presents a continuation of the research by Durst and Zieba from 2018 related to knowledge risks and their potential outcomes. This present study reviewed the up-dated literature on knowledge risks and uses the taxonomy proposed in the paper by Durst and Zieba to identify and analyse knowledge risks organizations are exposed to in the COVID-19 pandemics. Hence, the paper does not only offer fresh food for thought for researchers dealing with the topic of knowledge risks in the COVID-19 crisis and ways of handling them.

  • Knowledge Sharing in the COVID-19 Era of Remote Teaching: What Can Academia Learn from Business?
    • Krzysztof Zięba
    2021 Pełny tekst

    Purpose: The aim of this paper is to investigate how universities may benefit from experiences of businesses that were also forced to use remote forms of business operations. Methodology: The paper uses in-depth interviews to explore the possibilities of knowledge sharing improvements at the university-level teaching, based on the experiences elicited in the business sector. The theoretical sampling was used to find informants familiar with both transition to remote teaching and shift to online business operations forced by the COVID-19 pandemic. Findings: Interviews were conducted with experienced managers participating in an MBA programme. During the outburst of the COVID-19 pandemic the programme has been switched to a remote mode. At the same time, the interviewed managers had to cope with the transition to remote mode at work. Their work-related ordeals were contrasted and compared with their university-related experiences regarding knowledge sharing. Research limitations: This paper is of an exploratory character. The triangulation of findings presented here is limited. The sample consists of participants of one MBA programme only, hence the conclusions cannot be generalised. At this stage the paper may serve as a basis for further development. Practical implications: The paper presents possible improvements to be introduced by academia in the remote mode teaching. Business sector and especially large businesses may offer experience-based solutions that allow to boost knowledge sharing processes among students and increase the efficiency of knowledge sharing between teachers and students. Originality/value: The topic of the paper is very up-to-date and of considerable significance. Knowledge sharing processes at the university-level teaching have been significantly distorted by the COVID-19 pandemic outburst. Using experiences from the business sector can be very helpful in this regard.

  • Komputer w labiryncie
    • Michał Gleba
    • Grzegorz Godycki Ćwirko
    • Maryia Mankevich
    • Joanna Raczek
    2021 Pełny tekst Programista Junior

    Programiści piszą programy, które potrafią robić wiele różnych rzeczy: odtwarzać filmy, prognozować pogodę, pomagać w nauce języków obcych czy matematyki. Ale czy wiesz, że można zaprogramować komputer tak, aby tworzył labirynty? W dodatku takie, które zawierają tajne informacje!

  • Koncepcja Lean Management w uczelniach - przegląd wyników badań międzynarodowych
    • Piotr Grudowski
    2021

    W artykule przedstawiono rozważania dotyczące zastosowań koncepcji Lean Management w instytucjach szkolnictwa wyższego. Zaprezentowano odniesienia do charakterystycznych elementów i zasad tej koncepcji, przedstawione w piśmiennictwie międzynarodowym. Przedstawiono także szereg informacji wiążących się z LeanHE – rozwijającym się dynamicznie nurtem dotyczącym zastosowań Lean Management w szkolnictwie wyższym.

  • Kriging metamodels and design re‐utilization for fast parameter tuning of antenna structures
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2021 INTERNATIONAL JOURNAL OF NUMERICAL MODELLING-ELECTRONIC NETWORKS DEVICES AND FIELDS

    The paper addresses the problem of computationally efficient electromagnetic (EM)‐driven design closure of antenna structures. The foundations of the presented approach are fast kriging interpolation metamodels, utilized for two purposes: (a) producing a good starting point for further parameter tuning, and (b) yielding a reasonable Jacobian matrix estimate to jump‐start the optimization procedure. The models are rendered using available designs, for example, obtained from the previous design work with the same antenna structure. The low cost of design closure is ensured by employing Broyden‐based trust‐region gradient search along with the aforementioned Jacobian initialization. Our methodology is demonstrated using two planar antennas, a dual‐band uniplanar dipole and a quasi‐Yagi with a parabolic reflector, both optimized within wide ranges of operating conditions (center frequencies, the dielectric permittivity of the antenna substrate). The re‐design process requires only a handful of EM analyses of the respective structure. The presented framework can be viewed as a convenient algorithmic tool that capitalizes on the existing information on the structure at hand to enable warm‐start parameter tuning.

  • Kształcenie kadr dla gospodarki wodnej na Wydziale Inżynierii Lądowej i Środowiska Politechniki Gdańskiej
    • Tomasz Kolerski
    2021 Pełny tekst Gospodarka Wodna

    Politechnika Gdańska jest częścią europejskiej i światowej wspólnoty akademickiej. Wspólnota Uczelni działa na rzecz podnoszenia dobrostanu społecznego oraz zrównoważenia ekosystemu Ziemi – we współpracy z uczelniami z Europy i świata, a także z podmiotami z innych sektorów. Kształcenie i edukacja realizowane są na 8 wydziałach w ramach 37 kierunków I i II stopnia. Blisko 1300 nauczycieli akademickich kształci przeszło 15 tysięcy studentów z ponad 70 krajów. Uczelnia jest na 2. miejscu w konkursie MNiSW oraz zajmuje 4. miejsce wśród uczelni technicznych w rankingu szkół wyższych miesięcznika Perspektywy. Politechnika Gdańska jest również dostrzegana w rankingach międzynarodowych w tym Academic Ranking of World Universities (Ranking Szanghajski) oraz w prestiżowym zestawieniu najlepszych uczelni na świecie – QS World University Rankings 2021. Politechnika Gdańska oferuje możliwości uzyskania stopnia doktora w dwóch jednostkach: szkole doktorskiej oraz szkole doktorskiej wdrożeniowej, które są bezpłatne, zapewniają stypendium, są interdyscyplinarne i zapewniają kreatywne i interdyscyplinarne podejście do badań. Absolwenci Politechniki Gdańskiej łatwo znajdują pracę i są zadowoleni z wybranej uczelni, a ich wynagrodzenie zalicza się do 1) Dr hab. inż. Tomasz Kolerski, prof. uczelni, Politechnika Gdańska, Wydział Inżynierii Lądowej i Środowiska. najwyższych w kraju. Potwierdzają to nie tylko wyniki corocznego badania losów zawodowych osób, które ukończyły studia na PG, ale i zestawienie przygotowane przez zewnętrzną firmę.

  • Kwasy nukleinowe - niedoceniane składniki żywności
    • Zuzanna Koziara
    • Anna Kościelak
    • Agnieszka Bartoszek-Pączkowska
    2021 Laboratorium

    Obecnie badania nad kwasami nukleinowymi koncentrują się na roli genetycznej tych makromolekuł. Można jednak przypuszczać, że DNA jak i RNA powszechnie występujące w żywności mają także ważne znaczenie żywieniowe. Świadczy o tym obecność w układzie pokarmowym szeregu mechanizmów odpowiedzialnych za detekcję, trawienie i przyswajanie tych składników pokarmu. W literaturze naukowej rośnie liczba doniesień sugerujących istotną rolę żywieniową spożywanych kwasów nukleinowych, ale wiedza ta jest daleka od uporządkowania i nie dostarcza jeszcze ugruntowanych poglądów, które mogłyby stanowić podstawę rekomendacji dietetycznych.

  • La Città Libera di Danzica: compromesso ragionevole o scommessa impossibile?
    • Luciano Segreto
    2021 Passato e presente. Rivista di storia contemporanea

    The article outlines the main economic ptoblems connected with the birth of the Free city of Danzig. In particular, it studies the complex relationships between the city, the Polish government, the League of Nations, and the Allies about the use of the port of Danzig and the increasing competition with the port of Gdynia, built by the Polish government with support of the French one and some french private companies.

  • Labour resources in Azerbeijan
    • Krystyna Gomółka
    2021

    The article aims to assess the changes of the Azerbaijani labour resources through deductive analysis of historical data and observation of changes in the structure of resources based on generally available macroeconomic data. Analysis shows that, during the period considered, the population of Azerbaijan increased, with a majority living in cities. Universal access to education enabled a growing group of Azerbaijanis to complete secondary education. The percentage of students increased by 35.17%. Following the retirement age increase, the number of economically active and employed people has grown. The unemployment rate, affecting particularly women, has also decreased. The positive migration balance has boosted labour resources since 2008, but the trend was halted by the COVID pandemic in 2020. Business closures have increased unemployment, whereas border closures reduced migration.

  • Ladder-Based Synthesis and Design of Low-Frequency Buffer-Based CMOS Filters
    • Waldemar Jendernalik
    • Jacek Jakusz
    • Grzegorz Blakiewicz
    2021 Pełny tekst Electronics

    Buffer-based CMOS filters are maximally simplified circuits containing as few transistors as possible. Their applications, among others, include nano to micro watt biomedical sensors that process physiological signals of frequencies from 0.01 Hz to about 3 kHz. The order of a buffer-based filter is not greater than two. Hence, to obtain higher-order filters, a cascade of second-order filters is constructed. In this paper, a more general method for uffer-based filter synthesis is developed and presented. The method uses RLC ladder prototypes to obtain filters of arbitrary orders. In addition, a set of novel circuit solutions with ultra-low voltage and power are proposed. The introduced circuits were synthesized and simulated using 180-nm CMOS technology of X-FAB. One of the designed circuits is a fourth-order, low-pass filter that features: 100-Hz passband, 0.4-V supply voltage, power consumption of less than 5 nW, and dynamic range above 60 dB. Moreover, the total capacitance of the proposed filter (31 pF) is 25% lower compared to the structure synthesized using a conventional cascade method (40 pF).

  • Lagrangian model of an isolated dc-dc converter with a 3-phase medium frequency transformer accounting magnetic cross saturation
    • Piotr Dworakowski
    • Andrzej Wilk
    • Michał Michna
    • Alexis Fouineau
    • Martin Guillet
    2021 Pełny tekst IEEE TRANSACTIONS ON POWER DELIVERY

    This article presents a nonlinear equivalent circuit model of an isolated dc-dc converter with a 3-phase medium frequency transformer. The model takes into account the magnetic cross saturation of the 3-phase core-type magnetic circuit. The model is suitable in detailed electromagnetic transient simulations of power systems involving isolated dc-dc converters. The model is developed using the Lagrange energy method. It involves a matrix of dynamic inductances containing a nonlinear term resulting from core magnetization and a linear term resulting from leakage flux. The model parameters are determined based on a series of magnetostatic finite element method simulations. This approach is convenient when applied to high power transformers offering a limited characterization effort, or if the transformer prototype does not exist. The experimental validation performed on a novel 3-phase MFT prototype in a 100kW 1.2kV 20kHz dual active bridge converter has proved the validity of the model and model parameters. The no-load steady-state and inrush tests and the full-load test show a very good fit between the simulated and experimentally measured waveforms. The comparison with a classical simplified model neglecting magnetic cross saturation shows a significant difference in the no-load inrush test.

  • Landscape as a Potential Key Concept in Urban Environmental Planning: The Case of Poland
    • Aleksandra Sas-Bojarska
    2021 Pełny tekst Urban Planning

    Rapid urban development increases the consumption of materials, energy, and water, resulting in an overproduction of waste and emissions. These cause many environmental threats, such as ozone layer depletion and rain acidification, leading to climate change. Therefore, the question arises on how to improve the effectiveness of tools that strengthen environmental protection. This discursive article presents an approach stressing the role of landscape in environmental protection in Poland. It indicates that landscape protection is an ecological, not just an aesthetic activity, as it is often considered in Poland. The landscape reflects all changes occurring in individual elements of the environment resulting from urban development. Through landscape transformations, one can track the growth and accumulation of adverse effects in the chain of environmental changes. Knowledge regarding the dynamics and scope of these transformations can improve ecological design and technologies. Therefore, the landscape condition should be treated as an indicator of sustainable development. If so, one could hypothesise that effective landscape protection contributes to minimising environmental and climate changes. The relationships between the landscape and environmental/climate threats discussed in this article prompt combining some tools related to these threats, which may ensure both effective landscape protection and sustainable development, leading to reduced climate change. The possibilities and benefits of integrating these tools are presented here as well. General considerations are supplemented with references to the situation in Poland to support the need for implementing a more policy-oriented and interdisciplinary approach to landscape protection.

  • Large Hall and Nernst responses from thermally induced spin chirality in a spin-trimer ferromagnet
    • Kamil Kolincio
    • Max Hirschberger
    • Jan Masell
    • Shang Gao
    • Akiko Kikkawa
    • Yasujiro Taguchi
    • Taka-hisa Arima
    • Naoto Nagaosa
    • Yoshinori Tokura
    2021 Pełny tekst PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA

    The long-range order of noncoplanar magnetic textures with scalar spin chirality (SSC) can couple to conduction electrons to produce an additional (termed geometrical or topological) Hall effect. One such example is the Hall effect in the skyrmion lattice state with quantized SSC. An alternative route to attain a finite SSC is via the spin canting caused by thermal fluctuations in the vicinity of the ferromagnetic ordering transition. Here, we report that for a highly conducting ferromagnet with a two-dimensional array of spin trimers, the thermally generated SSC can give rise to a gigantic geometrical Hall conductivity even larger than the intrinsic anomalous Hall conductivity of the ground state. We also demonstrate that the SSC induced by thermal fluctuations leads to a strong response in the Nernst effect. A comparison of the sign and magnitude of fluctuation–Nernst and Hall responses in fundamental units indicates the need for a momentum–space picture to model these thermally induced signals.

  • Laser-assisted approach for improved performance of Au-Ti based glucose sensing electrodes
    • Adrian Olejnik
    • Gerard Śliwiński
    • Jakub Karczewski
    • Jacek Ryl
    • Katarzyna Siuzdak
    • Katarzyna Grochowska
    2021 APPLIED SURFACE SCIENCE

    This paper focuses on the synthesis route and electrochemical properties of electrocatalytic material based on gold nanoparticles (NPs) embedded in a structured titanium template obtained via optimized anodization, chemical etching and laser processing. SEM inspection reveals the presence of Au NPs (60–90 nm in diameter) sited in the titanium foil cavities. Performed electrochemical measurements enable nomination of the set of working laser parameters that allow for fabrication of material possessing the highest performance towards glucose oxidation. It is proven that laser-engineered electrodes have an improved stability in acidic conditions and higher response from glucose oxidation in both alkaline and neutral environment in comparison to analogs obtained by conventional furnace dewetting. In neutral electrolyte it is also observed that the current density increases by almost 300% while the change in mechanism of glucose oxidation was identified due to laser treatment. It is suggested that laser dewetted gold nanoparticles have more surface defects than furnace dewetted ones so that more AuOHads species are created and therefore catalytic activity of the material is enhanced. These results indicate a scalable and cost-effective fabrication route and are important for the current research on nonenzymatic glucose sensors.