2021 - Repozytorium publikacji - Politechnika Gdańska

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Publikacje z roku 2021

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Transparency of publicly available information about fiscal and monetary policy in Poland
- Maria Jastrzębska
2021 Pełny tekst
Research background: The quality of information provided by fiscal and monetary authorities are important in a democratic state. Ensuring fiscal policy transparency reduces fiscal risk and corruption and promotes public acceptance of fiscal reforms. Ensuring transparency in monetary policy allows market participants to anticipate central bank responses and take their effects into account when making investment and consumption decisions. Aim of the article: The aim of the article is to evaluate the transparency of information provided to the public by the fiscal and monetary authorities in Poland in the light of international standards of fiscal and monetary policy transparency and to propose changes to increase it. Methods: Qualitative analysis, deductive and inductive reasoning were used. The assessment of the level of transparency of publicly available information on fiscal and monetary policy in Poland was based on the analysis of the implementation of good practices formulated by the International Monetary Fund and the open budget index calculated by the International Budget Partnership. Findings and added value: There are no publications in the national literature dealing with the transparency of publicly available information on fiscal and monetary policies in the context of coordination of these policies. Poland lacks transparent message about public finance, with particular emphasis on the state budget, which would allow citizens to control the government's fiscal policy actions. There is a lack of transparent information about the operations of the NBP in relation to the government. There is a lack of clear, reliable and complete information for citizens about the coordination of actions taken by the fiscal and monetary authorities in Poland to achieve specific objectives of the state's financial policy.
Trends shaping innovations in the aerosol market
- Norbert Piotrowski
2021 Pełny tekst World Aerosols. The Voice of the Aerosol Industry
New hygiene regimes and sustainability commitments are helping to shape the aerosol market. Norbert Piotrowski of Aerosol Service Poland explains the thinking behind the company’s latest hygiene innovations.
Triazoloacridone C-1305 impairs XBP1 splicing by acting as a potential IRE1α endoribonuclease inhibitor
- Sylwia Bartoszewska
- Jarosław Króliczewski
- David Crossman
- Aneta Pogorzelska
- Maciej Bagiński
- James F. Collawn
- Rafal Bartoszewski
2021 Pełny tekst CELLULAR & MOLECULAR BIOLOGY LETTERS
Inositol requiring enzyme 1 alpha (IRE1α) is one of three signaling sensors in the unfolding protein response (UPR) that alleviates endoplasmic reticulum (ER) stress in cells and functions to promote cell survival. During conditions of irrevocable stress, proapoptotic gene expression is induced to promote cell death. One of the three signaling stressors, IRE1α is an serine/threonine-protein kinase/endoribonuclease (RNase) that promotes nonconventional splicing of XBP1 mRNA that is translated to spliced XBP1 (XBP1s), an active prosurvival transcription factor. Interestingly, elevated IRE1α and XBP1s are both associated with poor cancer survival and drug resistance. In this study, we used next-generation sequencing analyses to demonstrate that triazoloacridone C-1305, a microtubule stabilizing agent that also has topoisomerase II inhibitory activity, dramatically decreases XBP1s mRNA levels and protein production during ER stress conditions, suggesting that C-1305 does this by decreasing IRE1α’s endonuclease activity.
Tripping of F-type RCDs for high-frequency residual currents
- Hanan Tariq
- Stanisław Czapp
2021
Residual current devices (RCDs) are apparatus commonly used for protection against electric shock in low-voltage electrical installations. They protect people in the case of an earth fault or even in the case of direct contact with the live parts. However, to be effective protective devices, RCDs have to detect residual currents of various waveform shapes which appear in modern electrical installations. For this purpose, RCDs are classified into four types: AC; A; F and B. This paper is focused on F-type RCDs provided for the detection, in particular, of mixed-frequency residual currents. According to the standard referring to the F-type RCDs, they are tested by manufacturers under the non-sinusoidal waveform having components generated by control equipment supplied from a single-phase. In this paper, results of two tripping tests (other than normative) of F-type RCDs are presented. During the first test, waveforms having components generated by control equipment supplied from three phases were forced. During the second test, high-frequency pure sinusoidal residual currents were generated. Results of these tests have shown that F-type RCDs may detect mixed-frequency residual currents other than the normative but may not react to sinusoidal currents of frequencies higher than 1 kHz.
Tunable Dielectric Switching of (Quinuclidinium)[MnCl4] Hybrid Compounds
- Natalia Wójcik
- Dorota A. Kowalska
- Monika Trzebiatowska
- Ewelina Jach
- Adam Ostrowski
- Waldemar Bednarski
- Marek Gusowski
- Piotr Staniorowski
- Agnieszka Ciżman
2021 Pełny tekst Journal of Physical Chemistry C
Inorganic−organic hybrid QMnCl (Q = quinuclidinium) crystals were synthesized and characterized. The X-ray and variable-temperature IR/Raman analysis demonstrate that the crystals undergo a reversible structural phase transition, which originates from an order−disorder process and is related to the dynamics of the organic Q cation. Dielectric function measurements disclose a switchability between low (“OFF”) and high (“ON”) dielectric states centered at around 285 K. Owing to a remarkable temperature-dependent dielectric function, this type of molecular compound can represent an interesting tunable and switchable dielectric material for a diverse range of applications.
Two bacterial small heat shock proteins, IbpA and IbpB, form a functional heterodimer
- Artur Piróg
- Francesca Cantini
- Łukasz Nierzwicki
- Igor Obuchowski
- Bartłomiej Tomiczek
- Jacek Czub
- Krzysztof Liberek
2021 Pełny tekst JOURNAL OF MOLECULAR BIOLOGY
Small heat shock proteins (sHsps) are a conserved class of ATP-independent chaperones which in stress conditions bind to unfolded protein substrates and prevent their irreversible aggregation. Substrates trapped in sHsps-containing aggregates are efficiently refolded into native structures by ATP-dependent Hsp70 and Hsp100 chaperones. Most γ-proteobacteria possess a single sHsp (IbpA), while in a subset of Enterobacterales, as a consequence of ibpA gene duplication event, a two-protein sHsp (IbpA and IbpB) system has evolved. IbpA and IbpB are functionally divergent. Purified IbpA, but not IbpB, stably interacts with aggregated substrates, yet both sHsps are required to be present at the substrate denaturation step for subsequent efficient Hsp70-Hsp100-dependent substrate refolding. IbpA and IbpB interact with each other, influence each other’s expression levels and degradation rates. However, the crucial information on how these two sHsps interact and what is the basic building block required for proper sHsps functioning was missing. Here, based on NMR, mass spectrometry and crosslinking studies, we show that IbpA-IbpB heterodimer is a dominating functional unit of the two sHsp system in Enterobacterales. The principle of heterodimer formation is similar to one described for homodimers of single bacterial sHsps. β-hairpins formed by strands β5 and β7 of IbpA or IbpB crystallin domains associate with the other one's β-sandwich in the heterodimer structure. Relying on crosslinking and molecular dynamics studies, we also propose the orientation of two IbpA-IbpB heterodimers in a higher order tetrameric structure.
Two complementary approaches for the synthesis and isolation of stable phosphanylphosphaalkenes
- Aleksandra Ziółkowska
- Natalia Szynkiewicz
- Łukasz Ponikiewski
2021 Pełny tekst Inorganic Chemistry Frontiers
Phospha-Wittig (phosphanylphosphinidene titanium(IV) complex) and phospha-Peterson (lithiated diphosphane) reactions were used to obtain phosphanylphosphaalkenes with the general formula XYC=P-PtBu2 (X = alkyl, aryl group or H; Y = alkyl or aryl group). Therefore, two series of reactions with different ketones and aldehydes were performed. An examination revealed that the two methods are complementary. For smaller carbonyl compounds, the phospha-Wittig reaction was shown to be a much better method, while for larger substituents (mainly aromatic), the phospha-Peterson reaction was shown to be a reliable method. These studies led to, among other things, the isolation of seven phosphanylphosphaalkenes in crystalline form after the phospha-Peterson reaction: (Ph)2C=P-PtBu2 (3a), Z-(Ph)(4-CN-Ph)C=P-PtBu2 (3c), (4-CN-Ph)2C=P-PtBu2 (3d), (4-MeO-Ph)2C=P-PtBu2 (3e), E-tBu(Ph)C=P-PtBu2 (3f), E-{(Me)2N-Ph}(H)C=P-PtBu2 (4d) and E-PhPh(H)C=P-PtBu2 (4e). Corresponding compounds were obtained at high yields under mild conditions, and more importantly, these new species are relatively air- and absolutely moisture-stable, especially these originating from aldehydes aldehyde. Additionally, a comprehensive DFT study helped us to establish not only the key factors crucial for the effective phospha-Wittig-based synthesis of C=P-P species but also the consecutive steps along the reaction path leading to the formation of these compounds.
Two-photon microperimetry with picosecond pulses
- Marcin Marzejon
- Łukasz Kornaszewski
- Jakub Bogusławski
- Piotr Ciąćka
- Miłosz Martynow
- Grażyna Palczewska
- Sebastian Maćkowski
- Krzysztof Palczewski
- Maciej Wojtkowski
- Katarzyna Komar
2021 Pełny tekst Biomedical Optics Express
Two-photon vision is a phenomenon associated with the perception of short pulsesof near-infrared radiation (900-1200 nm) as a visible light. It is caused by the nonlinear processof two-photon absorption by visual pigments. Here we present results showing the influence ofpulse duration and repetition rate of short pulsed lasers on the visual threshold. We comparedtwo-photon sensitivity maps of the retina obtained for subjects with normal vision using acost-effective fiber laser (λc=1028.4 nm,τp=12.2 ps,Frep=19.17 MHz) and a solid-state laser(λc=1043.3 nm,τp=0.253 ps,Frep=62.65 MHz). We have shown that in accordance with thedescription of two-photon absorption, the average optical power required for two-photon visionfor a fiber laser is 4 times greater than that for a solid-state laser. Mean sensitivity measured forthe first one is 5.9±2.8 dB lower than for the second but still 17 dB away from the safety limit,confirming that picosecond light sources can be successfully applied in microperimetry. Thisdevelopment would dramatically reduce the cost and complexity of future clinical devices
Two-Row ESPAR Antenna with Simple Elevation and Azimuth Beam Switching
- Mateusz Rzymowski
- Łukasz Kulas
2021 Pełny tekst IEEE Antennas and Wireless Propagation Letters
In this letter, we propose a two-row electronically steerable parasitic array radiator (ESPAR) antenna designed for direction of arrival (DoA) estimation in Internet of Things (IoT) applications relying on simple microcontrollers. The antenna is capable of elevation and azimuth beam switching using a simple microcontroller-oriented steering circuit and provides 18 directional radiation patterns, which can be grouped in 3 distinctive sets having different directions in the elevation. For each elevation direction, there are 6 different beam configurations that cover 360 degrees in the horizontal plane. Measurements of the realized antenna prototype carried out in an anechoic chamber show good agreement with numerical simulations. The antenna prototype provides low side lobe level (SLL), low half power beam width (HPBW) in both elevation and horizontal directions, and exhibit monotonous drop from the maximum value for all 18 radiation patterns. Therefore, the antenna is a good candidate for IoT nodes capable of DoA estimation in situations when radio frequency (RF) signals are impinging the antenna from different directions in elevation.
Two-step synthesis of niobium doped Na–Ca–(Mg)–P–Si–O glasses
- Natalia Wójcik
- S Ali
- Aleksandra Mielewczyk-Gryń
- B Jonson
2021 Pełny tekst JOURNAL OF MATERIALS SCIENCE
Niobium doped biosolubility glasses in the Na–Ca–(Mg)–P–Si–O system were prepared by using an untypical two-step synthesis route. The parent glass was melted in air atmosphere at 1350 °C followed by re-melting the glass in Nb crucible with the addition of metallic Mg/Ca powder in the nitrogen atmosphere. The second melting step was carried out at 1450–1650 °C, using an induction furnace. The topography and structure of the obtained glasses were characterized by confocal microscopy, X-ray powder diffraction and infrared spectroscopic techniques. The chemical compositions were examined by energy-dispersive X-ray spectroscopy (EDS). The glasses were found to be of grayish color, X-ray amorphous and having network connectivity between * 2.5 and 2.7. The network connectivity of re-melted glasses was lower than the one of the parent glass. The glass structure consists of a highly disrupted silicate network of predominantly Q2 groups as well as isolated orthophosphate tetrahedra. The parent glass contains nanocrystallites consisted of apatitic PO43- groups. The re-melted glasses contain nonapatitic or amorphous calcium phosphates. The obtained glass transition temperatures range from 530 to 568 °C and exhibit higher values for glassed doped with Ca metal. These glasses have improved thermal stability as compared to reference bioglasses. The biosolubility test in phosphate buffered saline solution (PBS) confirms that the glasses have biosolubility properties and HAp formation on the surfaces was observed
Twórczość - przekraczanie dyscyplin. Analiza postawy autorskiej
- Agnieszka Kurkowska
2021 Pełny tekst Facta Ficta. Journal of Theory, Narrative & Media
Agnieszka Kurkowska w artykule Twórczość - przekraczanie dyscyplin. Analiza postawy autorskiej odnosi się do zagadnienia poruszania w różnych obszarach wiedzy i umiejętności przez jednostkowego twórcę. Zarysowany jest problem niemożności wąskiego traktowania architektury jako dziedziny stricte inżynieryjnej. Architekt otwarty na otaczające problemy przestrzenne, ich fizyczne i pozafizyczne aspekty sięga w swoich wypowiedziach do obszarów pokrewnych architekturze, aby swoją wypowiedź wzmocnić i wzbogacić. W poniższej pracy podjęto próbę udowodnienia tezy, że przeanalizowana tu postawa autorska ukazuje konieczność przekraczania dyscyplin w projektowaniu architektonicznym. Ukazano, w oparciu o studium przypadku, w jaki sposób poruszanie się poza ścisła inżynierią może wzbogacać projekty architekta i wzmacniać możliwość ich oddziaływania. Na dobrane do prezentowanej analizy projekty składają się projekty obiektów architektonicznych, projekty małej architektury, mebli, przedmiotów użytkowych, wnętrz. To również projekty artystyczne posiłkujące się malarstwem, grafiką, rzeźbą, fotografią czy instalacją przestrzenną, także publikacje książkowe. Kolejną kategorią są projekty edukacyjne skoncentrowane na cyklach działań warsztatowych, materiałach edukacyjnych, wydarzeniach partycypacyjnych. Wszystkie przykłady łączy osoba autora, poruszającego się w swojej pracy w obszarze kilku dyscyplin, co w perspektywie czasowej ukazuje kompletną, wieloelementową postawę wobec przestrzeni, korzystających z niej ludzi i wypełniających ją obiektów. Wspomniana postawa zawiera kilka istotnych komponentów, które przeważając w określonych przypadkach, przenoszą go do poszczególnych zadań i związanych z nimi ról społecznych i zawodowych. Bywa więc architekt twórcą, gdy posługuje się narzędziami wyrazu artystycznego, kreując indywidualne, unikalne obiekty w różnej skali, poruszając się jednocześnie w obszarze sztuki i inżynierii. Może też być naukowcem, czy badaczem analizujący, pogłębiający, poszukującym, weryfikujący przyjęte rozwiązania. Czasami staje się pedagogiem czy edukatorem, gdy swoje działania skupia na przekazaniu wiedzy. Ponad wszystko architekt pozostaje jednakże człowiekiem o określonej strukturze psychicznej i fizycznej, będąc osobowym elementem społeczności. Architekt to autor przekraczający różne dyscypliny w ramach swojej twórczości czego konieczności i celowości mają dowieść przedstawione analizy i wspierające je studium przypadku.
Type III Responses to Transient Inputs in Hybrid Nonlinear Neuron Models
- Jonathan E. Rubin
- Justyna Signerska-Rynkowska
- Jonathan D. Touboul
2021 Pełny tekst SIAM JOURNAL ON APPLIED DYNAMICAL SYSTEMS
Experimental characterization of neuronal dynamics involves recording both of spontaneous activity patterns and of responses to transient and sustained inputs. While much theoretical attention has been devoted to the spontaneous activity of neurons, less is known about the dynamic mechanisms shaping their responses to transient inputs, although these bear significant physiological relevance. Here, we study responses to transient inputs in a widely used class of neuron models (nonlinear adaptive hybrid models) well-known to reproduce a number of biologically realistic behaviors. We focus on responses to transient inputs that have been previously associated with Type III neurons, arguably the least studied category in Hodgkin's classification, which are those neurons that never exhibit continuous firing in response to sustained excitatory currents. The two phenomena that we study are postinhibitory facilitation, in which an otherwise subthreshold excitatory input can induce a spike if it is applied with proper timing after an inhibitory pulse, and slope detection, in which a neuron spikes to a transient input only when the input's rate of change is in a specific, bounded range. Using dynamical systems theory, we analyze the origin of these phenomena in nonlinear hybrid models. We provide a geometric characterization of dynamical structures associated with postinhibitory facilitation in the system and an analytical study of slope detection for tent inputs. While the necessary and sufficient conditions for these behaviors are easily satisfied in neurons with Type III excitability, our proofs are quite general and valid for neurons that do not exhibit Type III excitability as well. This study therefore provides a framework for the mathematical analysis of these responses to transient inputs associated with Type III neurons in other systems and for advancing our understanding of these systems' computational properties.
Typology and comparative analysis of black tents built in tradition of iranian tribes
- Najmeh Hassas
2021 Pełny tekst
This study focused on the habits and way of life of nomads in the Iranian Highlands, but their homes, called Black Tents, were of the main interest. The research explored the construction of the Black Tents and the way of shaping the space in which family life takes place. It concerned the architectural forms of tents, structures and materials from which they are erected, as well as interior furnishings and objects that determine their character. The methods used in the research include descriptive analysis and graphical presentation of the test results. The inquiry was conducted in libraries, archives and institutions and using official websites. The author also conducted drawing and photographic inventories of tents and everyday life of nomads. Laboratory tests of the next phase of work have been documented with printouts and presentations of the sets of devices used in the research. Further analysis was carried out using advanced software computer programmes, such as 3DMax, ABAQUS and other professional civil engineering digital tools allowing to obtain comparable results. The research results and summaries of their individual phases are presented in the form of maps, charts and tables. As a result of macroscopic studies, it turned out that the fabric, made of cloth woven from long black goat hair, with which the structures are covered (Chador), which is woven by women, is the same for all tribes. Women also erect and dismantle tents before and after the journey and so have an influence on their construction. The analysis of the dimensions and forms of the discussed seven types of tents from different parts of the country showed large differences, which is evidence of creativity and engineering thinking. The next step of the research was to check to what extent the stability of each tent is adjusted to the climatic situation in which it is used. For this purpose, models were created in the ABACUS program. Their responses to wind and rain loads have been studied. It has been confirmed that the tents are strictly adapted to the conditions in which they are used. Their diversification is the result of the experience of many generations of nomads: observing the routes they traveled and the materials they could use. Tests of tent models covered with hand-made goat hair fabric showed that it is more useful for strengthening the structure of the tent and protecting its interior than fabrics used today for a similar purpose.
UAV Photogrammetry under Poor Lighting Conditions—Accuracy Considerations
- Paweł Burdziakowski
- Katarzyna Bobkowska
2021 Pełny tekst SENSORS
The use of low-level photogrammetry is very broad, and studies in this field are conducted in many aspects. Most research and applications are based on image data acquired during the day, which seems natural and obvious. However, the authors of this paper draw attention to the potential and possible use of UAV photogrammetry during the darker time of the day. The potential of night-time images has not been yet widely recognized, since correct scenery lighting or lack of scenery light sources is an obvious issue. The authors have developed typical day- and night-time photogrammetric models. They have also presented an extensive analysis of the geometry, indicated which process element had the greatest impact on degrading night-time photogrammetric product, as well as which measurable factor directly correlated with image accuracy. The reduction in geometry during night-time tests was greatly impacted by the non-uniform distribution of GCPs within the study area. The calibration of non-metric cameras is sensitive to poor lighting conditions, which leads to the generation of a higher determination error for each intrinsic orientation and distortion parameter. As evidenced, uniformly illuminated photos can be used to construct a model with lower reprojection error, and each tie point exhibits greater precision. Furthermore, they have evaluated whether commercial photogrammetric software enabled reaching acceptable image quality and whether the digital camera type impacted interpretative quality. The research paper is concluded with an extended discussion, conclusions, and recommendation on night-time studies.
Uczelnia organizacją z domieszka turkusu - sznasa czy iluzja?
- Krzysztof Leja
- Aleksandra Pawlak
2021 Pełny tekst e-mentor
Po kilkuletnich dyskusjach nad przyszłym kształtem szkolnictwa wyższego w Polsce, zarówno na poziomie systemowym, jak i instytucjonalnym, w 2018 r. uchwalono ustawę Prawo o szkolnictwie wyższym i nauce, zwaną dalej Ustawą (2018). Regulacja ta wraz z pakietem rozporządzeń poszerzyła autonomię uczelni w zakresie organizacyjno-zarządczym, jednocześnie potęgując znaczenie ich rozliczalności. Wzmocnienie władzy rektora spowodowało zmianę postrzegania uczelni jako organizacji rozproszonych (Weick, 1976) w kierunku organizacji zwartych (Brunsson i Sahlin-Andersson, 2000) Autorzy opracowania dostrzegli, że koncepcja uczelni, zgodnie z literą i duchem Ustawy, nie zwraca należytej uwagi na relacje między pracownikami. Dlatego za cel artykułu uznano przedstawienie propozycji wdrożenia do instytucji akademickiej elementów coraz częściej opisywanej w literaturze naukowej – a równocześnie budzącej skrajne emocje – koncepcji organizacji turkusowej (Laloux, 2015). W artykule wskazano niewykorzystane, zdaniem autorów, możliwości zmian organizacyjno-zarządczych, jakie stworzyła Ustawa, a także opisano wybrane cechy organizacji turkusowej, odnosząc je do instytucji akademickiej. Ponadto zestawiono cechy uniwersytetu tradycyjnego, przedsiębiorczego oraz uniwersytetu z domieszką turkusu. W części badawczej przeanalizowano wywiady przeprowadzone z celowo wybranymi pracownikami Politechniki Gdańskiej, którzy wyrażali opinie dotyczące nowych rozwiązań organizacyjno-zarządczych zaproponowanych przez współautorkę artykułu podczas wywiadów. W podsumowaniu starano się odpowiedzieć na pytanie sformułowane w tytule.
Uczelnie kształcące polskich inżynierów elektryków do II wojny światowej
- Dariusz Świsulski
2021 Pełny tekst Przegląd Elektrotechniczny
Na podstawie notek biograficznych ponad 1000 osób przedstawiono uczelnie, w których wykształcenie w latach 1891-1935 zdobywali polscy inżynierowie elektrycy. Do I wojny światowej były to uczelnie zagraniczne: niemieckie, rosyjskie, francuskie, belgijskie. Później Polacy kształcili się w polskich uczelniach: Politechnice Lwowskiej oraz w utworzonej w 1915 roku i szybko rozwijającej się Politechnice Warszawskiej.
Ukrainian Market of Electrical Energy: Reforming, Financing, Innovative Investment, Efficiency Analysis, and Audit
- Ruslan Kostyrko
- Tetiana Kosova
- Lidiia Kostyrko
- Liudmyla Zaitseva
- Oleksandr Melnychenko
2021 Pełny tekst ENERGIES
The aim of this research is to determine the influence of electrical energy market regulation reform in Ukraine on the competitive environment, the reproduction processes of financial and innovative support, and the energy efficiency of the national economy. The authors have put forward and verified the hypothesis that, under conditions of institutional maturity of the Ukrainian electrical energy market, its liberalization and separation of the kinds of activity related to generation, transmission, and distribution leads to a decrease in prices, and the level of economic concentration stimulates implementation of innovations and the formation of reports on sustainable development. Over the thirteen-year time interval, a steady trend of decreasing energy intensity of the Ukrainian economy was established, and the appropriateness of energy efficiency management based on strategic targets was substantiated. The electricity market model in Ukraine is defined as a hybrid one, with an emphasis on trade under bilateral agreements. It was statistically found that liberalization of the electrical energy market in Ukraine contributed to a decrease in prices, with the exception of the areas of largest household and non-household consumers. The high level of asset concentration in the accounts of large enterprises was revealed, and the conclusion concerning the improvement of the competitive environment in the electricity production sector and the existence of the features of natural monopolies in the areas of transmission and distribution of electricity was made. The assessment of the financial competitive ability and profitability of electrical energy market entities was made, the main entities of the investment activity and the sources of their financing were characterized, and innovations were emphasized. The role of the standards of the audit of integrated reporting of the Ukrainian energy holdings and their role in ensuring sustainable development was determined.
Ulepszanie podłoża gruntowego i podtorza z użyciem środków strzałowych
- Eligiusz Mieloszyk
- Anita Milewska
- Mariusz Wyroślak
2021
Szybka i skuteczna metoda wzmacniania podłoża gruntowego i podtorza z wykorzystaniem środków strzałowych (zastrzeżona nazwa handlowa: metoda mikrowybuchów) pozwala projektować i budować drogi kolejowe na gruntach o obniżonej nośności (np. tereny podmokłe, bagna, odpady przemysłowe, komunalne, zdegradowane nasypy antropogeniczne). Jest przydatna i godna polecenia przy budowie nowych linii kolejowych, modernizacji istniejących oraz naprawach bieżących i głównych (często powiązanych z modernizacją). Prawidłowo wzmocnione podłoże gruntowe i podtorze jest gwarantem niezawodności danej linii kolejowej. Zwiększa żywotność trasy i bezpieczeństwo prowadzonego ruchu kolejowego.
Ultimate compressive strength assessment of uncleaned and cleaned corroded plates with locked crack
- Krzysztof Wołoszyk
- Yordan Garbatov
2021 Pełny tekst Polish Maritime Research
The work presented here investigates the structural response of cleaned corroded plates, subjected to compressive load in the presence of a locked crack, where the change of mechanical properties as a result of corrosion development and the cleaning process is also accounted for. A Finite Element model for assessing the compressive strength, considering geometric and material nonlinearities, is developed, and the analysed plates are compared with the available experimental data. An experimental design plan is generated using the Design of Experiments techniques, which quantifies the influence of the governing variables and their interactions with respect to the plate's ultimate compressive strength. With a limited number of observations, the most significant effects are identified. The corrosion degradation is revealed to be the most crucial effect leading to an effective strength reduction. It was found that, in the case of a corroded plate with a locked crack subjected to a compressive load, the most severe case is when the crack is transversely oriented. The strength reduction is slightly lower than when the corrosion degradation and the presence of a crack are considered to be a simple summation of these two effects but acting separately. The outcome of the analysis is the development of several empirical formulations that allow a fast estimation of the ultimate strength of a corroded plate, subjected to compressive load in the presence of a locked crack, accounting for different cleaning.
Ultimate strength of stiffened plates subjected to compressive load and spatially distributed mechanical properties
- Krzysztof Wołoszyk
- Yordan Garbatov
2021
The present study deals with the ultimate strength of stiffened plates subjected to spatially distributed mechanical properties and compressive load. Normally, mean values of mechanical properties based on tensile tests are used to validate the numerical assessment with experimental results. However, mechanical properties may vary within a single specimen. To investigate the impact of that, random fields of yield stress and Young modulus are employed together with the FE method. The variations of mechanical properties are estimated based on tensile tests. Different parameters of the random field are analysed, showing that the structural response will be different when compared with the stiffened plate with constant mechanical properties. Finally, it was revealed that the variation of yield stress has a significant impact, and Young modulus uncertainties play a secondary role. It is concluded, that the spatial variation of mechanical properties need to be considered when validating the numerical assessment with experimental measurements.