Publications Repository - Gdańsk University of Technology

Page settings

polski
Publications Repository
Gdańsk University of Technology

Show publications from the year

Recent items

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  • Economics of credit scoring management
    • Błażej Kochański
    2019

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

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

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

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

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

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

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

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

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

  • EFEKTYWNOŚĆ EKONOMICZNA HYBRYDOWEJ MIKROINSTALACJI OZE
    • Elżbieta Bogalecka
    • Zbigniew Krzemiński
    2019 Full text Zeszyty Naukowe Wydziału Elektrotechniki i Automatyki Politechniki Gdańskiej

    W artykule przedstawiono warunki pracy mikroelektrowni hybrydowej zainstalowanej w małej firmie mieszczącej się na terenie przemysłowym. Pokazano strukturę i parametry elektrowni składającej się z paneli fotowoltaicznych i elektrowni wiatrowej. Przeanalizowano odbiorniki energii oraz warunki pobierania mocy biernej. Dla wybranego okresu czasu pokazano zużycie oraz produkcję energii elektrycznej i energię zużytą na potrzeby firmy oraz oddaną do sieci. Na podstawie cen energii określono czas zwrotu nakładów inwestycyjnych już poniesionych. Zbadano celowość modernizacji przekształtników w elektrowni polegającej na wymianie tranzystorów IGBT na tranzystory SiC i celowość zakupu magazynu energii. Wykazano, że poniesione nakłady zwrócą się po ponad 10 latach. Nieuchronny wzrost cen energii spowoduje skrócenie czasu zwrotu nakładów inwestycyjnych do mniej niż 10 lat.

  • Efektywność przewodowego transportu paliw gazowych. Część 1
    • Waldemar Kamrat
    • Adam Kielak
    2019 Full text Ciepłownictwo, Ogrzewnictwo, Wentylacja

    W pracy przeprowadzono badanie możliwości podwyższenia efektywności transportu rurociągowego gazu ziemnego. Przeanalizowano różnorodne aspekty z zakresu procedur projektowania. Zaproponowano modele określania kosztów kapitałowych (inwestycyjnych) i kosztów zmiennych. Określono równania jednostkowych kosztów całkowitych (rocznych), które poddano „quasi-optymalizacji”, w celu wyznaczenia średnic racjonalnych dla gazociągów.

  • Efektywność przewodowego transportu paliw gazowych. Część 2
    • Waldemar Kamrat
    • Adam Kielak
    2019 Full text Ciepłownictwo, Ogrzewnictwo, Wentylacja

    W pracy przeprowadzono badanie możliwości podwyższenia efektywności transportu rurociągowego gazu ziemnego. Przeanalizowano różnorodne aspekty z zakresu procedur projektowania. Zaproponowano modele określania kosztów kapitałowych (inwestycyjnych) i kosztów zmiennych. Określono równania jednostkowych kosztów całkowitych (rocznych), które poddano „quasi-optymalizacji”, w celu wyznaczenia średnic racjonalnych dla gazociągów.

  • Effect of aeration of antibiotic-loaded bone cement on its properties and bactericidal effectiveness
    • Anna Pałubicka
    • Jakub Czubek
    • Marcin Wekwejt
    2019 Full text Minerva Ortopedica E Traumatologica

    BACKGROUND: Antibiotic-loaded bone cements are now widely used in medicine. They are able to locally deliver antibiotic particles and they allow treat or protect against infection. It is assumed that the bactericidal effectiveness of bioactive bone cements depend on the parameters of its production. Hence, the aim of this study was to check the effect of aeration of bone cement before mixing the components on its properties as well as its effectiveness in combating infections. METHODS: The following research was carried out: preparation of specimens of commercially available bone cement with different aeration time, assessment of the obtained structure, porosity analysis, measurement of wettability, as well as, bactericidal tests (zone of bacterial growth inhibition and optical density of the bacterial solution). RESULTS: The results show that the process of aeration of bone cement improve the open-pore structure of bone cement, its porosity and in effect enables better inhibition of bacterial growth. However, longer aeration time resulted in defects in the structure that may contribute to fatigue breaks. Future research should undertake a broader investigation of mechanical properties, determination of the released dose of antibiotic and potential optimization of the aeration process of bone cement. CONCLUSIONS: The additional step in the form of aeration during the production of bone cement enables to modify its structure and improvement of bactericidal properties, which will result in better infection treatment (in the so-called shock dose).

  • Effect of coarse grain aggregate on strength parameters of two-stage concrete
    • Farzam Omidimoaf
    • Ali M. Rajabi
    • Hakim S. Abdelgader
    • Marzena Kurpińska
    • Krzysztof Wilde
    2019 Full text Materiały Budowlane

    . Two-stage concrete (TSC) is a special type of concrete that the method of its construction and implementation is different from conventional one. In TSC, coarse aggregate particles are first placed in the formwork and voids between them are subsequently injected with a special cementations mixture. TSC has been successfully used in many applications, such as underwater construction, casting concrete sections congested with reinforcement and concrete repair. Coarse aggregate forms about 60% of the total volume of TSC, while coarse aggregate forms about 40% of the total volume of conventional concrete. In TSC stresses are transferred through contact areas between coarse aggregate particles. In this paper coarse aggregate size influence on strength parameters of TSC and comparing it with conventional concrete is done (by uniaxial compressive strength test and Brazilian tensile strength test). According to results of tests in this paper, the TSC with finest grain of coarse aggregate has higher compressive and tensile strength, higher modulus of elasticity and less Poisson’s ratio from conventional concrete.

  • Effect of manufacturing errors of the pad sliding surface on the performance of the hydrodynamic thrust bearing
    • Loukas Zoupas
    • Michał Wodtke
    • Christos Papadopoulos
    • Michał Wasilczuk
    2019 Full text TRIBOLOGY INTERNATIONAL

    In the present study, investigation of the effect of manufacturing errors on the performance of large tilting pad thrust bearings has been performed, following a CFD-based Thermohydrodynamic analysis of a single pad. A 3D model has been generated, including the pad, the lubricant film and the corresponding part of the collar. The pad has been assumed to be deformed about the pivot point, due to thrust loading. Manufacturing errors of different type and amplitude have been superimposed. The equilibrium position of the pad has been calculated by a Newton-Raphson iterative procedure. The principal performance parameters of the bearing (minimum film thickness, friction torque, maximum pressure and temperature) have been calculated. The results demonstrate that manufacturing errors may affect substantially bearing performance, and should be taken into consideration in the design of large tilting pad thrust bearings.

  • Effect of operating conditions on N 2 O production in an anammox sequencing batch reactor containing granular sludge
    • Tiago D. S. Pereira
    • Carla E. D Santos
    • Lu Xi
    • Hussein Al-Hazmi
    • Joanna Majtacz
    • Eduardo C. Pires
    • Márcia H. R.Z. Damianovic
    • Jacek Mąkinia
    2019 WATER SCIENCE AND TECHNOLOGY

    Nitrous oxide (N2O) is one of the gases with the greatest impact in the atmosphere due to its persistence and significant contribution to the greenhouse effect. This study provides an insight into the dynamics of N2O production in wastewater nitrogen removal systems. A 10 L sequencing batch reactor containing enriched anammox biomass was subjected to different operational conditions, i.e., temperature, feed time, NO2 /NH4 þ ratio and the initial concentrations of NH4 þ and NO2 . Tests showed no significant differences in maximum N2O production when the system was operated with a shorter feed time and no increase in the operating temperature. A higher N2O production was observed when the initial NO2 /NH4 þ ratio increased from 1.3 to 1.7 and 1.9. The highest initial concentration of NO2 was linked to an increase in residual N2O at the end of the batch cycle, probably due to heterotrophic denitrifying metabolism

  • Effect Of Resveratrol And Quercetin On Telomerase Regulation In Cancer Cells And Their Anti-Cancer Potential
    • Wioletta Brankiewicz
    2019

    Telomeres and telomerase are nowadays one on targets for anticancer therapy. Telomerase is expressed in ~90% of human cancer cell lines and tumor specimens, whereas its enzymatic activity is not detectable in most human somatic cells. Was found that some dietary compounds can modulate telomerase activity in cancer cells. This review summarizes the current knowledge about the effects of resveratrol and quercetin on telomerase regulation in cancer cells.

  • Effect of selective laser treatment on initiation of fatigue crack in the main part of an undercarriage drag strut
    • Anna Bień
    • Marek Szkodo
    • Jerzy Doberski
    • Bartłomiej Karpiński
    2019 Full text Chinese Journal of Aeronautics

    This paper presents the results of material characterization and a fatigue test conducted for a laser-re-melted drag strut used in an aircraft landing gear. The drag strut was re-melted with a CO2 laser beam. Eight re-melted paths were made in the form of spiral lines along the axis of the drag strut. Next, the drag strut was subjected to variable loads on a testing machine simulating loads occurring when an aircraft lands. The fatigue test showed that the laser-treated drag strut was able to withstand 1700 simulated cycles of landing. This result was 70% better than that obtained for a drag strut with no laser treatment. In order to find the reason for the increase in the number of cycles of simulated landings, tests were carried out using transmission and scanning electron microscopes, a computer microtomograph, an X-ray diffractometer, and a nanoindenter, respectively. Results of the conducted research indicated that the reasons for the increased fatigue life of the laser-treated undercarriage drag strut were both an ultra-fine cellular martensitic microstructure and compressing residual stresses generated during the laser re-melting of the surface layer of the material.

  • Effect of soil moisture on current-carrying capacity of low-voltage power cables
    • Stanisław Czapp
    • Filip Ratkowski
    2019 Full text Przegląd Elektrotechniczny

    One of the factors affecting current-carrying capacity of underground power cables is the thermal resistivity of soil. Its value in the close proximity of the cable is the most important, and for this reason, in some cases, the local soil is replaced with an another soil type or with a cement-sand mixture. The thermal resistivity of the soil is strongly affected by moisture, and in the case of a cement-sand mixture – as tested by the authors – also by this mixture initial water content. The paper presents results of investigation of soil moisture influence on the soil thermal resistivity, and an analysis of the current-carrying capacity of a low-voltage power cable for various soil parameters, in particular its part directly surrounding the cable.

  • Effect of solar radiation on current-carrying capacity of PVC-insulated power cables – the numerical point of view
    • Stanisław Czapp
    • Seweryn Szultka
    • Adam Tomaszewski
    • Agata Szultka
    2019 Full text Tehnicki Vjesnik-Technical Gazette

    Power cables are usually buried in the soil, which results in their relatively high current-carrying capacity. However, there are cases in which the starting/final section of a cable line runs along a pole of an overhead power line. Power cables can be directly exposed to solar radiation then, and this negatively influences their current-carrying capacity as well as estimated life of the cables’ insulation. An analysis of thermal phenomena in PVC-insulated low-voltage power cables, exposed to solar radiation, is conducted in the paper. Current-carrying capacity of an example cable system, for various placements of the cables, is evaluated. The analysis has shown that solar radiation may significantly reduce current-carrying capacity of PVC-insulated cables. A possible method of protection of cables against solar radiation, and its effectiveness, is presented. To investigate the mentioned thermal phenomena, a Computational Fluid Dynamics (CFD) has been used.

  • Effect of Storage Conditions of Rutile Flux Cored Welding Wires on Properties of Welds
    • Aleksandra Świerczyńska
    2019 Full text Advances in Materials Science

    The influence of storage locations of two grades of rutile flux cored welding wires on their surface condition and the strength of the welds made with them were studied. Wires were stored in real urban conditions (Gdańsk and Katowice) for 1 month, simultaneously recording changes in conditions: temperature and relative humidity of the environment. Visual tests of wires in the delivered and stored condition as well as visual and tensile strength tests of welds made with them were carried out. It was found that the surface of the wires underwent more intense degradation (atmospheric corrosion) during storage in Katowice than in Gdańsk. Significant difference in tensile strength was observed only for padding welds made using Gdańsk stored wires. The lowest recorded tensile strength value was not lower than the standard requirements for the wires.

  • Effect of the Catalytic Center on the Electron Transfer Dynamics in Hydrogen-Evolving Ruthenium-Based Photocatalysts Investigated by Theoretical Calculations
    • Magdalena Staniszewska
    • Stephan Kupfer
    • Julien Guthmuller
    2019 Full text Journal of Physical Chemistry C

    The light-induced relaxation pathways in the molecular photocatalyst [(tbbpy)2Ru(tpphz)PtCl2]2+ are investigated with time-dependent density functional theory calculations together with the Marcus theory of electron transfer (ET). The calculations show that metal (Ru) to ligand (tpphz) charge transfer (MLCT) triplet states are populated following an excitation in the longer wavelength range of the absorption spectrum, but that an ET toward the catalytic center (PtCl2) from these states is thermodynamically unfavorable, implying that charge separation can only occur via higher energy states in this system. Moreover, low-lying Pt-centered states can be populated and the calculations predict that they can form an excited state equilibrium with MLCT states localized on the tpphz ligand. A comparison with previously reported results for the photocatalyst [(tbbpy)2Ru- (tpphz)PdCl2]2+, based on a PdCl2 catalytic center, is provided in order to decipher the effect of the catalytic center on their respective photochemistry (Staniszewska, M.; Kupfer, S.; Guthmuller, J. Chem.Eur. J. 2018, 24, 11166−11176).

  • Effect of the North Atlantic Thermohaline Circulation on changes in climatic conditions and river flow in Poland
    • Wrzesiński Dariusz
    • Marsz Andrzej
    • Anna Styszyńska
    • Leszek Sobkowiak
    2019 Full text Water

    : The purpose of this study is to find connections between the North Atlantic Thermohaline Circulation (NA THC), climate elements, such as cloud cover, precipitation, air temperature, sunshine duration, and relative humidity, and flow of rivers in Poland. The intensity of NA THC was characterized by the DG3L index, which was established to assess changes in the amount of heat transported by NA THC along with the transport of water to the Arctic. The paper explains and discusses the mechanism of impact of the NA THC changeability on the elements of the catchment water balance variability. The positive and negative phases of the DG3L index are strongly correlated with the heat anomalies in the upper layer of the North Atlantic waters. The obtained results show that changes of NA THC have significant impact on weather conditions and selected climate elements in Poland. Statistically significant positive correlations were found between the DG3L index and average annual air temperatures, particularly in April, July, and August, while negative between the DG3L index and the total cloud cover. Consequently, in the years with the positive values of the DG3L index, there are favorable conditions for the strong increase in evaporation and evapotranspiration from the ground surface. This has impact on flow of rivers in Poland, which shows considerable regional differences.

  • Effect of the welding environment and storage time of electrodes on the diffusible hydrogen content in deposited metal
    • Jacek Tomków
    • Dariusz Fydrych
    • Grzegorz Rogalski
    • Jerzy Łabanowski
    2019 Full text REVISTA DE METALURGIA

    In the study the glycerin displacement method was used for determination of diffusible hydrogen content in deposited metal. Specimens were welded in the air and in the water with covered rutile electrodes. The first part of the specimens was made immediately after opening the package of the electrodes. The electrodes were then stored in opened packages in laboratory conditions that allowed for contact with the air for three years. After that time, the second part of the samples was made. The results of the measurements of the diffusible hydrogen amount in deposited metal ranged from 32.61 to 39.95 ml/100 g for specimens welded in the air and from 51.50 to 61.34 ml/100 g for specimens made in the water. The statistical analyses were performed in a Statistical software package using the ANOVA module (one-way analysis of variance) with an assumed significance level α = 0.05. The assumption of normality was verified by the Shapiro-Wilk test. The homogeneity of variance was verified by the Levene test. In the next step, post-hoc analyzes were made. The aim was to determine which averages are significantly different. Scheffe, Tukey, NIR Fisher, Newman-Keuls and Duncan tests were used. Possible changes in the diffusible hydrogen content in deposited metal resulting from storage time of electrodes (3 years) were verified by Student’s t-test. All of the statistical analysis shows that the storage time of the electrodes has no significant influence on the diffusible hydrogen content in deposited metal regardless of the welding environment.

  • Effective configuration of a double triad planar parallel manipulator for precise positioning of heavy details during their assembling process
    • Krzysztof Lipiński
    2019 Full text

    In the paper, dynamics analysis of a parallel manipulator is presented. It is an atypical manipulator, devoted to help in assembling of heavy industrial constructions. Few atypical properties are required: small workspace; slow velocities; high loads. Initially, a short discussion about definition of the parallel manipulators is presented, as well as the sketch of the proposed structure. In parallel, some definitions, assumptions and equations are presented for the used multibody methodology. The main part of the paper presents results of the numerical tests performed in order to determinate the best work configuration of the proposed structure. It is verified, that with the initially proposed one, not all of the work requirements are satisfied, mainly about the load distribution. Obtained numerical results are confirmed by some diagrammatic simplified analysis of the load distribution. With the same diagrammatic method, alternative configurations are proposed and verified numerically, next. At the end, final configuration is presented as the one satisfying the requirements.

  • Effective degradation of sulfide ions and organic sulfides in cavitation-based Advanced Oxidation Processes (AOPs)
    • Michał Gągol
    • Reza Soltani
    • Andrzej Przyjazny
    • Grzegorz Boczkaj
    2019 Full text ULTRASONICS SONOCHEMISTRY

    The paper presents the results of investigations on the effectiveness and reaction rate constants of the oxidation of sulfide ions and organic sulfides in real industrial effluents from the production of bitumens (2000 mg S2- L-1) using hydrodynamic and acoustic cavitation. The content of the effluents was analysed in terms carbon disulfide, dimethyl sulfide, and di-tert-butyl disulfide concentration. A possibility of complete oxidation of sulfides by cavitation alone as well as by its combination with external oxidants such as hydrogen peroxide, ozone or peroxone was demonstrated. The oxidation time for the most effective processes is as little as 15 min. Due to the presence of sulfide ions, the effluents from the production of bitumens were oxidized at a strongly alkaline pH. The results of this study reveal the advantage of performing advanced oxidation processes (AOPs) at a basic pH. The effective degradation of sulfide ions enables performance of further degradation of organic contaminants at an acidic pH, ensuring high efficiency of treatment based, for example, on the Fenton reaction without the risk of release of hydrogen sulfide to the atmosphere. The results of this research are applicable to all kinds of caustic effluents for which the lack of possibility of pH adjustment limits their efficient treatment.

  • Effective Formula for Impact Damping Ratio for Simulation of Earthquake-induced Structural Pounding
    • Seyed Khatami
    • Hosein Naderpour
    • Rui Barros
    • Anna Jakubczyk-Gałczyńska
    • Robert Jankowski
    2019 Full text Geosciences

    Structural pounding during earthquakes may cause substantial damage to colliding structures. The phenomenon is numerically studied using different models of collisions. The aim of the present paper is to propose an effective formula for the impact damping ratio, as a parameter of the impact force model used to study different problems of structural pounding under seismic excitations. Its accuracy has been verified by four various approaches. Firstly, for the case of collisions between two structural elements, the dissipated energy during impact has been compared to the loss of kinetic energy. In the second stage of verifications, the peak impact forces during single collision have been analyzed. Then, the accuracy of different equations have been verified by comparing the impact force time histories for the situation when a concrete ball is dropped on a rigid concrete surface. Finally, pounding between two structures during earthquakes has been studied. The results of the analysis focused on comparison between dissipated and kinetic energy show relatively low errors between calculated and assumed values of the coefficient of restitution when the proposed equation is used. In addition, the results of the comparison between experimentally and numerically determined peak impact forces during single collision confirm the effectiveness of the approach. The same conclusion has been obtained for the whole impact time history for collision between a ball and a rigid surface. Finally, the results of the comparative analysis, conducted for pounding between two structures during an earthquake, confirm the simulation accuracy when the proposed approach is used. The above conclusions indicate that the proposed formula for impact damping ratio, as a parameter of impact force model for simulation of earthquake-induced structural pounding, is very effective and accurate in numerical simulations in the case of different scenarios.

  • Effective Friction Angle Of Deltaic Soils In The Vistula Marshlands
    • Kamila Międlarz
    • Jakub Konkol
    • Lech Bałachowski
    2019 Full text Studia Geotechnica et Mechanica

    This article presents the results of laboratory tests on soft, normally consolidated soils from the Vistula Marshlands. Samples of high-plasticity organic soils (muds) taken from 3.2–4.0 m and 9.5–10.0 m depth, as well as peat deposit at 14.0 m, are analysed. Presented case study confirms the applicability of the Norwegian Institute of Technology (NTH) method based on Cone Penetration Tests (CPTU) and allows for a conservative estimation of effective friction angle for muds. The plastification angle equal to 14.5° for organic silt, applied in the modified NTH method, fits well the triaxial test (TX) results. Moreover, the dilative-contractive behaviour according to the CPTU soil classification based on the Robertson’s proposal from 2016 corresponds well with volumetric changes observed in the consolidated drained triaxial compression tests. The internal friction angles of the Vistula Marshlands’ muds and peats are lower in comparison with the database of similar soft soils.

  • Effective yttrium based coating for steel interconnects of solid oxide cells: Corrosion evaluation in steam-hydrogen atmosphere
    • Sebastian Molin
    • Å.h. Persson
    • T.l. Skafte
    • A.l. Smitshuysen
    • S.h. Jensen
    • K. H. Andersen
    • H. Xu
    • Ming Chen
    • Peter Vang Hendriksen
    2019 JOURNAL OF POWER SOURCES

    This work describes manufacture, analysis and test of a new well conducting corrosion-protection coating that can be applied on steel types with high chromium content. Electrolytic deposition of yttrium salts is used to form thin (<100 nm) coatings on both flat steel sheets (material: Crofer 22 APU) and its properties are proven on woven wire-meshes (materials from two different sources: SUS316 and SUS316L). The oxide scale on the coated Crofer 22 APU sheet remains intact after 2000 h operation at 750 °C in H2 with 90% H2O. The corrosion rate at 750 °C of the coated Crofer 22 APU sheets is compared with that of uncoated samples and of samples with a commercial magneton sputtered CGO coating revealing that the coatings reduce the parabolic rate constant characteristic of the corrosion by a factor of 10 and 20 for the CGO and the Y, respectively.

  • Effects of electrophoretic deposition times and nanotubular oxide surfaces on properties of the nanohydroxyapatite/nanocopper coating on the Ti13Zr13Nb alloy
    • Michał Bartmański
    • Andrzej Zieliński
    • Magdalena Jażdżewska
    • Joanna Głodowska
    • Pamela Kalka
    2019 CERAMICS INTERNATIONAL

    Load-bearing implants are developed with a particular emphasis placed on an application of ceramic hydroxyapatite coatings in order, to enhance the bioactivity of titanium implants and to shorten the healing time. Therefore, thin, fully crystalline coatings that are, highly adhesive, hydrophilic and demonstrating antibacterial properties are ly looked for. The aim of this research was to develop and characterize the properties of (nano)hydroxyapatite coatings implemented with nanocopper particles and obtained by the electrophoretic method. The deposition was carried out on the Ti13Zr13Nb alloy, either on a bare surface or a nanotubular oxide layer. The deposition was made for 1 or 2 min. The chemical composition, phase composition, coating structure, homogeneity, thickness, nanoindentation and nanomechanical properties, adhesion determined by a nanoscratch test, and wettability measured by a contact angle were investigated. The presence of nanotubular oxide layers caused no significant change in nanoindentation and nanomechanical propertie and an increase in adhesion strength and a decrease in the contact angle. The increase in deposition time resulted in an increased thickness, a decreased hardness, an increased adhesion strength and wettabilty. The observed effects in the composite (nano)HAp/Cu – (nano)TiO2 coatings are attributed to the change in the structure of coatings following the increasing deposition time and coating thickness.

  • Effects of mechanical stress on electrical arameters and noise of supercapacitors
    • Arkadiusz Szewczyk
    • Łukasz Lentka
    • Janusz Smulko
    2019 Full text

    Results of noise and electrical parameters measurements of prototype electrochemical double layer capacitors (EDLC) are reported at the presence of selected mechanical stress. This issue is of great importance due to future applications in wearable technology. The measurement results are compared, and we may conclude than flicker noise is more sensitive to any stress than other considered electrical parameters.

  • Effects of Na+, K+ and B3+ Substitutions on the Electrical Properties of La10Si6O27 Ceramics
    • Sea-Fue Wang
    • Yung-Fu Hsu
    • Yi-Le Liao
    • Ting-Ting Yang
    • Piotr Jasiński
    2019 JOURNAL OF ELECTRONIC MATERIALS

    Doping of Na and K at La sites and of B at Si site in La10Si6O27 with oxyapatite structure and fabrication of their ceramics were made by the solid-state reaction method. It was found that partial substitution of Na+ and K+ on La sites decreased the sinterability of the La10Si6O27 based ceramics, whereas partial substitution of B3+ on the Si site improved the sinterability. Na+ and K+ substitutions in La10−xNaxSi6O27−x and La10−xKxSi6O27−x can suppress second-phase La2SiO5 formation, and, in this study, as the x value of the two substitutions reached 0.7 and 0.5, respectively, the La2SiO5 phase disappeared. Doping of Na+, K+, and B3+ all displayed the hindering effect of grain growth during sintering. Compositions of La9.3Na0.7Si6O26.3, La9.5K0.5Si6O26.5, and La10Si5.5B0.5O26.75 revealed the highest electrical conductivity in each system. La10Si5.5B0.5O26.75 ceramic sintered at 1575°C showed the highest electrical conductivity at temperatures above 600°C among all the apatite ceramics evaluated. The electrical conductivities of La10Si5.5B0.5O26.75 at 700°C and 800°C reported 0.011 S cm−1 and 0.024 S cm−1, respectively, which are superior or comparable to previous studies, and their activation energies for conduction were calculated to be 0.80 eV.

  • Effects of Na+, K+ and B3+ Substitutions on the Electrical Properties of La10Si6O27 Ceramics
    • Sea-Fue Wang
    • Yung-Fu Hsu
    • Yi-Le Liao
    • Ting-Ting Yang
    • Piotr Jasiński
    2019 ECS Transactions

    Doping of Na and K at La sites and of B at Si site in La10Si6O27 with oxyapatite structure and fabrication of their ceramics were made by solid-state reaction method. It was found that partial substitution of Na+ and K+ on La sites decreased the sinterability of the La10Si6O27 based ceramics, whereas partial substitution of B3+ on Si site imporved the sinterability. Na+ and K+ substitutions in La10-xNaxSi6O27-x and La10-xKxSi6O27-x were found to suppress second-phase La2SiO5 formation. La10Si5.5B0.5O26.75 ceramic sintered at 1575ºC showed the highest electrical conductivity at temperatures above 600ºC among all the apatite ceramics evaluated. The electrical conductivities of La10Si5.5B0.5O26.75 at 700ºC and 800ºC reported 0.011 and 0.024 S cm-1, respectively, which are superior or comparable to previous studies, and their activation energies for conduction were calculated to be 0.80 eV.

  • Effects of n-butanol presence, inlet loading, empty bed residence time and starvation periods on the performance of a biotrickling filter removing cyclohexane vapors from air
    • Piotr Rybarczyk
    • Bartosz Szulczyński
    • Milena Gospodarek
    • Jacek Gębicki
    2019 Full text CHEMICAL PAPERS

    This paper presents the results of investigations on the removal of cyclohexane vapors from air using a peat-perlite packed biotrickling filter. Effects of basic process parameters i.e. IL (inlet loading) and EBRT (empty bed residence time) as well as introduction of n-butanol to the treated air stream and starvation periods on the process performance were evaluated. The results show that the introduction of hydrophilic n-butanol results in an enhanced removal of hydrophobic cyclohexane comparing to the experiments where only cyclohexane was treated. Additionally, the biotrickling filter performance after the starvation events is regained to more extent for mixed system than for the single cyclohexane. A novel and interesting element of the paper is the application of an electronic nose for the process monitoring. Obtained results are discussed in the perspective of an influence of the presence of a compound with different affinity to aqueous phase on the removal efficiency of the compound with opposite chemical properties.

  • Effects of Road Infrastructure on Pedestrian Safety
    • Marcin Budzyński
    • Lucyna Gumińska
    • Kazimierz Jamroz
    • Tomasz Mackun
    • Piotr Tomczuk
    2019 Full text IOP Conference Series: Materials Science and Engineering

    The objective of the work was to identify risks for pedestrians that involve road infrastructure and roadside and to define how selected elements of geometry and traffic layout affect driver behaviour (speed on approaching pedestrian crossings). The results have helped to formulate recommendations on pedestrian crossing design. The research included an analysis of 2013-2017 statistics to identify the circumstances and causes of pedestrian accidents. Field work at about 2,000 unsignalized pedestrian crossings was the basis for assessing the safety of these crossings. Assessment criteria were selected and a safety classification was made with specific recommendations made for possible treatments. More field work was designed to measure speeds near pedestrian crossings in three cases: no pedestrians in the crossing area, a pedestrian is approaching a crossing, a pedestrian is waiting to cross the road. The study was conducted in different areas (city, transit roads passing through small towns, non-built-up areas) for different cross-sections (one carriageway and two lanes –1x2, two carriageways with two or three lanes each –2x2, 2x3, one carriageway and four lanes –1x4). The study also looked at speed limits –50 and 70 km/h. The share of drivers giving way to pedestrians waiting to cross was also assessed. Pedestrians were surveyed and asked about how safe they feel crossing the road. The survey also asked drivers about driver behaviour and use of speed management measures.Statistical analyses show the circumstances and causes of pedestrian accidents

  • Efficiency and proportions of waste tyre pyrolysis products depending on the reactor type—A review
    • Witold Lewandowski
    • Katarzyna Januszewicz
    • Wojciech Kosakowski
    2019 Full text JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS

    This article discusses the current use of different pyrolytic reactors, their constructions and operating principles regarding the yields of main products of waste tyre pyrolytic recycling. Whether one makes a larger or smaller profit, or even a loss due to a surcharge being levied on waste tyre recycling, depends on the sale of the pyrolysis products (gas, char, oil), the proportions and market prices of which differ. The cheapest is gas, which can be used as a source of technological heat of energetically self-sufficient pyrolysis or after purification, can be burned in a boiler and converted into heat or electricity. Raw char is not expensive either. It requires upgrading and then, as carbon black, can be re-used for the production of tyres or in the form of improved carbon can be used as an absorber or catalyst. The most expensive is oil, containing mainly aromatic compounds, on the condition that it will not be burned as diesel or liquid fuel. Hence, the oil yields obtained in various types of pyrolysers are given. This review of pyrolysis reactors is organised according to the criterion of charge movement in the reactor and the means of bringing this about. Depending on the method and speed of movement of the load in reactors, they are classified as fixed-bed and movable-bed reactors. The latter group is subdivided, depending on the method of inducing this movement, into pneumatic (bubbling, spouted, circulating or transport fluidised beds), mechanical (rotary kiln, rake, auger, ablative, stirred) reactors and reactors in which the charge moves under gravity. This review focuses on the construction and operating principles of the reactors and the yields of the products of pyrolytic thermal decomposition of scrap tyres. The summary and comparison of main product yields (oil/ gas/coal) obtained in different reactors and by different authors, presented in graphical and tabular form, constitute a summary and supplement to this work.

  • Efficient Finite Element Analysis of Axially Symmetrical Waveguides and Waveguide Discontinuities
    • Małgorzata Warecka
    • Rafał Lech
    • Piotr Kowalczyk
    2019 Full text IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES

    A combination of the body-of-revolution and finite element methods is adopted for full-wave analysis of waveguides and waveguide discontinuities involving angular field variation. Such an approach is highly efficient and much more flexible than analytical techniques. The method is performed in two different cases: utilizing a generalized impedance matrix to determine the scattering parameters of a single waveguide section and utilizing periodic boundary conditions without sources. In order to confirm the validity and efficiency of both approaches, a few examples of axially symmetrical structures have been analyzed. The obtained results are compared to those obtained from commercial software and available in the literature.

  • Efficient Gradient-Based Algorithm with Numerical Derivatives for Expedited Optimization of Multi-Parameter Miniaturized Impedance Matching Transformers
    • Sławomir Kozieł
    • Anna Pietrenko-Dąbrowska
    2019 Full text RADIOENGINEERING

    Full-wave electromagnetic (EM) simulation tools have become ubiquitous in the design of microwave components. In some cases, e.g., miniaturized microstrip components, EM analysis is mandatory due to considera¬ble cross-coupling effects that cannot be accounted for otherwise (e.g., by means of equivalent circuits). These effects are particularly pronounced in the structures in¬volving slow-wave compact cells and their numerical opti¬mization is challenging due to expensive simulations and large number of parameters. In this paper, a novel gradi¬ent-based procedure with numerical derivatives is pro¬posed for expedited optimization of compact microstrip impedance matching transformers. The method restricts the use of finite differentiation which is replaced for se¬lected parameters by a rank-one Broyden updating for¬mula. The usage of the formula is governed by an ac¬ceptance parameter which is made dependent on the pa¬rameter space dimensionality. This facilitates handling circuits of various complexities. The proposed approach is validated using three impedance matching transformer circuits with the number of parameters varying from ten to twenty. A significant speedup of up to 50 percent is demon¬strated with respect to the reference algorithm.

  • Efficient synthesis and antifungal investigation of nucleosides’ quaternary ammonium salt derivatives
    • Barbara Dmochowska
    • Lucyna Pellowska-Januszek
    • Justyna Samaszko
    • Rafał Ślusarz
    • Roland Wakieć
    • Janusz Madaj
    2019 Full text TURKISH JOURNAL OF CHEMISTRY

    Quaternary ammonium salts are a group of compounds with diverse biological properties, the most important of which are their antiviral, antibacterial, and antifungal activities. The quaternization reactions of 5'-O-tosyl derivatives of uridine and thymidine with triethylamine, trimethylamine, 4-(N ,N -dimethylamino)pyridine, 2-methylpyridine, and pyridine are described in this article. Two of the synthesized compounds are exceptional because they are first of this type that demonstrate concentration-dependent antifungal in vitro activity against two species of the genus Candida in minimal YNB-SG medium. The experimental results have been extended by adding full atom molecular dynamics simulations and substrates and products energies evaluation.

  • Ekonometryczna analiza konsumpcji w Polsce w latach 1995-2018- statyczne modele wydatków konsumpcyjnych w wartościach nominalnych
    • Jerzy Ossowski
    2019 Full text Przestrzeń Ekonomia Społeczeństwo

    W artykule przeprowadzono badania makroekonomicznych związków pomiędzy konsumpcją globalną (C) a produktem krajowym brutto (PKB). W części teoretycznej artykułu: • zdefiniowano postacie analityczne przyczynowo-skutkowych makromodeli konsumpcji, • sformułowano interpretację mierników opisujących badane zależności, • sformułowano założenia stochastyczne dla rozważanych makromodeli konsumpcji, W części empirycznej artykułu: • przeprowadzono analizę i interpretację danych statystycznych oraz podstawowych mierników charakteryzujących makroekonomiczne procesy konsumpcji w Polsce w latach 1995-2018, • oszacowano parametry strukturalne proponowanych wersji modeli, • przeprowadzono weryfikację oszacowanych wersji modeli, • zinterpretowano oszacowane i zweryfikowane mierniki. Ostatecznie w stosunku do konsumpcji ogółem (CON) oraz konsumpcji gospodarstw domowych (CN) wykazano, że w gospodarce polskiej w latach 1995-2018: • z każdego dodatkowego miliarda nominalnego produktu krajowego brutto (PKBN) społeczeństwo przeznaczało na konsumpcję ogółem (CON) około 0,744 miliarda złotych z przeciętnym błędem wynoszącym 0,034 miliarda złotych. • z każdego dodatkowego miliarda nominalnego produktu krajowego brutto (PKBN) gospodarstwa domowe przeznaczały na swoją indywidualną konsumpcję (CN) około 0,574 miliarda złotych z przeciętnym błędem wynoszącym 0,029 miliarda złotych.

  • Ekspertyza dotycząca wpływu tlenków żelaza na nowy rurociąg ze stali nierdzewnej gat. 1.4307 podwieszany pod mostem stalowym nad rzeką Wisłą, który jest połączony z dwóch stron z magistralą wodociągową wykonaną z rur z żeliwa szarego.
    • Łukasz Gaweł
    2019

    Przedmiotem niniejszej umowy jest dokonanie oceny wpływu na nowy rurociąg ze stali nierdzewnej (1.4307), związków żelaza rozpuszczonych w wodzie oraz związków żelaza odłożonych w starych przewodach z żeliwa szarego, a które to związki przemieszczają się pod wpływem zmian kierunku przepływu wody oraz uderzeń hydraulicznych. Ponadto przedmiot stanowi ocena wpływu produktów korozji na stan stali nierdzewnej i układu żeliwo/stal nierdzewna.

  • Elastic Fender-Dolphin Interaction for Economic Design of Berthing Dolphins
    • Waldemar Magda
    2019 JOURNAL OF WATERWAY PORT COASTAL AND OCEAN ENGINEERING-ASCE

    The study addresses the question of the possible design benefits when considering the interaction between a modern marine modular rubber fender and a steel tubular pile substructure of a berthing dolphin. Absorption of the berthing kinetic energy of the vessel by a dualelasticity pile-fender berthing system is described in detail using the interactive treatment method (ITM). Application of the ITM is illustrated by a calculative example, assuming a 37,700 deadweight ton (DWT) tanker as a berthing ship, realistic geometries of large-diameter steel piles of the berthing dolphin substructure, and a family of Sumitomo Pi-type modular rubber fender units. By splitting the berthing kinetic energy into two parts absorbed by two elastic component elements of the dual-elasticity system of the berthing dolphin, the ITM is an effective tool for proper selection of the minimum required size (i.e., outside diameter and wall thickness) of steel piles of the berthing dolphin substructure in relation to the size of fender unit assumed. Finally, using ITM, an example analysis is performed to illustrate the influence of fender size selection on the berthing force, and the mass and stiffness of the steel-pile substructure of the berthing dolphin, as meaningful parameters influencing the most economical solution in the berthing dolphin design.

  • Elastic scattering of electrons from chloroform
    • Borna Hlousek
    • M. F. Martin
    • Murtadha Khakoo
    • Mateusz Zawadzki
    • G. M. Moreira
    • L. S. Maioli
    • Marcio Bettega
    • L Machado
    • V. A. S. da Mata
    • A. J. da Silva
    • I Iga
    • M-T Lee
    • M Homem
    2019 Full text PHYSICAL REVIEW A

    We present experimental and theoretical cross sections for elastic electron scattering from CHCl3. This is an important target because of its relevance to environmental chemistry and the plasma etching industry as a source of chlorine radicals. The experimental results were obtained at incident electron energies ranging from 0.5 to 800 eV in the 10deg-130deg scattering angle range. Theoretically, the scattering cross sections in the low-energy region were obtained by using the Schwinger multichannel method with pseudopotentials in the static-exchange plus polarization approximation. Additionally, in the low- and intermediate-energy ranges, theoretical calculations were also performed using a molecular complex optical potential and a single-center expansion method combined with Padé approximation. Further calculations using the independent atom model were also made at intermediate energies. Momentum-transfer cross sections were derived by integrating the differential cross sections. In general, there is a good agreement between the experimental data and the theoretical results. Moreover, the calculations reveal the presence of three shape resonances in the elastic channel, located at 0.5, 2, and 8 eV. The two higher-lying resonances were confirmed by the present experiments, whereas the positions of the two lower-lying resonances agree well with previous results of electron attachment experiments.