2019 - Repozytorium publikacji - Politechnika Gdańska

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Dynamic tests of composite footbridge segment – experimental and numerical studies
- Tomasz Wiczenbach
- Tomasz Ferenc
- Łukasz Pyrzowski
- Jacek Chróścielewski
2019 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst
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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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 Pełny tekst 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.