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Search results for: STATIC IN VITRO DISSOLUTION
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Antibacterial Porous Systems Based on Polylactide Loaded with Amikacin
PublicationThree porous matrices based on poly(lactic acid) are proposed herein for the controlled release of amikacin. The materials were fabricated by the method of spraying a surface liquid. Description is given as to the possibility of employing a modifier, such as a silica nanocarrier, for prolonging the release of amikacin, in addition to using chitosan to improve the properties of the materials, e.g., stability and sorption capacity....
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Utilizing Genome-Wide mRNA Profiling to Identify the Cytotoxic Chemotherapeutic Mechanism of Triazoloacridone C-1305 as Direct Microtubule Stabilization
PublicationRational drug design and in vitro pharmacology profiling constitute the gold standard in drug development pipelines. Problems arise, however, because this process is often dicult due to limited information regarding the complete identification of a molecule’s biological activities. The increasing aordability of genome-wide next-generation technologies now provides an excellent opportunity to understand a compound’s diverse eects...
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Charakterystyka tranzystorów z węglika krzemu w wysokosprawnych przekształtnikach
PublicationPółprzewodnikowe przyrządy mocy z węglika krzemu (SiC) osiągnęły poziom technologiczny umożliwiający powszechne stosowanie w układach przekształtnikowych. W artykule omówiono ostatnie osiągnięcia dotyczące układów przekształtnikowych z przyrządami z węglika krzemu oraz wybrane wyniki badań realizowane na Politechnice Gdańskiej. W artykule opisano właściwości statyczne i dynamiczne tranzystorów MOSFET i JFET z węglika krzemu oraz...
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Eksperymentalne i numeryczne badania parametrów dynamicznych trybuny stalowej
PublicationTrybuny stalowe to konstrukcje, które odnajdują swoje zastosowanie głównie podczas wydarzeń sportowych, koncertów muzycznych oraz innych wydarzeń, którym towarzyszą rytmiczne aktywności widzów i głośna muzyka. Ze względu na smukłość oraz lekkość elementów z jakich wykonana jest konstrukcja trybuny jest ona bardzo łatwo wzbudzana przez ludzi do drgań. Z przeprowadzonej w pracy [4] analizy modalnej wynika, że masa ludzi prowadzi...
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Modyfikacja kompozytów elastomerowych NR za pomocą ligniny i glicerolizatu
PublicationPrzedmiotem opisanych w niniejszym artykule badań są wulkanizaty kauczuku naturalnego. Celem pracy było zbadanie wpływu ligniny oraz glicerolizatu na wybrane właściwości kompozytów zawierających kauczuk naturalny. Strukturę chemiczną przygotowanych materiałów potwierdzono, wykorzystując analizę spektroskopową w podczerwieni (FTIR). Zbadano również właściwości mechaniczne przy statycznym rozciąganiu, twardość, ścieralność oraz odbojność...
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Morphology and properties of recycled polyethylene/ground tyre rubber/thermoplastic poly(ester-urethane) blends
PublicationThe growing amount of plastics waste produced every year resulted in development of mechanical and chemical recycling methods of polymers and their blends or composites. From the environmental point of view, the possibility of plastics waste reusing and recycling is desirable. In this study three polymer blends were obtained with using recycled polyethylene (RPE), ground tyre rubber (GTR) and thermoplastic poly(ester-urethane)...
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Morphology and the physical and thermal properties of thermoplastic polyurethane reinforced with thermally reduced graphene oxide
PublicationIn this study, thermally reduced graphene oxide (TRG)-containing polyurethane nanocomposites were obtained by the extrusion method. The content of TRG incorporated into polyurethane elastomer systems equaled 0.5, 1.0, 2.0 and 3.0 wt%. The morphology, static and dynamic mechanical properties, and thermal stability of the modified materials were investigated. The application of TRG resulted in a visible increase in material stiffness...
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The influence of temperature on properties of the polymer flexible joint used for strengthening historical masonries
PublicationA new method of repairing damaged structures by filling the cracks with a specially prepared elastomeric polymer mass has been recently proposed. This new and innovative technique, known as the Flexible Joint Method (FJM), is mainly dedicated to masonries and historical objects, where minimum intervention is permitted. The flexible joint bonds the disrupted elements and ensures further safe exploitation of a damaged structure....
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A study on microcrack monitoring in concrete: discrete element method simulations of acoustic emission for non-destructive diagnostics
PublicationThe research is focused on the monitoring of fracture evolution in concrete beams under three-point bending using the acoustic emission technique and the discrete element method. The main objective of the study was to numerically and experimentally investigate the mechanism behind the generation of elastic waves during acoustic emission events and their interaction with micro- and macro-cracking in concrete beams under monotonic...
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Computational modelling of historic masonry railroad arch bridges
PublicationThe problems encountered during the analyzes of structural response of historic masonry railroad arch bridges are described in this paper. The attention is mainly focused on the stiffness of the masonry arches, their strengths and appropriate estimation of railroad load intensity. Issues related to computational modelling of two, existing, almost 130 years old masonry arch railroad bridges are presented in this context. The main...
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Quasistatic and fatigue behavior of an AISI H13 steel obtained by additive manufacturing and conventional method
PublicationThis work aims to compare the mechanical behavior of an AISI H13 steel obtained by additive manufacturing with that obtained by conventional manufacturing methods. The average values of the ultimate tensile strength (UTS) and ductility obtained for the specimens produced by the conventional method were equal to 658 MPa and 18%, respectively, which compares with 503 MPa and 0.75% registered for the selective laser melting (SLM)...
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Multimedia interface using head movements tracking
PublicationThe presented solution supports innovative ways of manipulating computer multimedia content, such as: static images, videos and music clips and others that can be browsed subsequently. The system requires a standard web camera that captures images of the user face. The core of the system is formed by a head movement analyzing algorithm that finds a user face and tracks head movements in real time. Head movements are tracked with...
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An experimental study on polymer mass
PublicationA new method of repairing damaged structures by filling the cracks with specially prepared polymer mass has been recently proposed. The technique is mainly dedicated to historical objects where minimum intervention is permitted. The flexible joint bonds the disrupted elements and ensures further safe exploitation of a damaged structure. The aim of the present paper is to show the results of an experimental study on polymer mass...
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Evaluation of RTKLIB's Positioning Accuracy Using low-cost GNSS Receiver and ASG-EUPOS
PublicationThe paper focuses on a comparison of different positioning methods provided by free and open source software (FOSS) package called RTKLIB. The RTKLIB supports real‐time and post‐processed positioning. The most important modes of operation tested by the authors are Kinematic, Static, Fixed and Precise Point Positioning (PPP). The data for evaluation were obtained from low‐cost Global Navigation Satellite System (GNSS) receiver....
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Marine propeller shaft bearings under low-speed conditions: water vs. oil lubrication
PublicationThe bearings used in shipbuilding, hydropower, and water pumps have undergone a metamorphosis in recent decades. Because of environmental regulations, lubrication with grease or mineral oil is prohibited. Thus, the standard solutions include water-lubricated bearings with polymer bushings or sealed systems lubricated with oil. When properly designed, assembled, and operated, bearings can operate reliably for years. However, specific...
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PRELIMINARY FIELD TESTS AND LONG-TERM MONITORING AS A METHOD OF DESIGN RISK MITIGATION: A CASE STUDY OF GDAŃSK DEEPWATER CONTAINER TERMINAL
PublicationAppropriate risk assessment plays a fundamental role in the design. . The authors propose a possible method of design risk mitigation, which follows recommendations included in Eurocode 7. The so-called “Observational Method” (OM) can produce savings in costs and programmes on engineering projects without compromising safety. The case study presented is a complex design solution that deals with the heavy foundations of a gantry...
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Navigational decision support system during approach manoeuvre in emergency STS transfer operation
PublicationThe paper is concerned with the problem of safe trajectory planning for approaching during emergency STS (Ship to Ship) transfer operation with oil spill. The safe trajectory means that the way points does not cross in the area of the environment with the static and dynamic obstacles and at the same time satisfies ship's stopping and speed deceleration performance. The evolutionary path planning algorithm is used to determine trajectory...
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On the plastic buckling of curved carbon nanotubes
PublicationThis research, for the first time, predicts theoretically static stability response of a curved carbon nanotube (CCNT) under an elastoplastic behavior with several boundary conditions. The CCNT is exposed to axial compressive loads. The equilibrium equations are extracted regarding the Euler–Bernoulli displacement field by means of the principle of minimizing total potential energy. The elastoplastic stress-strain is concerned...
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SHORT REVIEW AND 3-D FEM ANALYSIS OF BASIC TYPES OF FOUNDATION FOR OFFSHORE WIND TURBINES
PublicationSome problems of the foundations of offshore wind turbines are considered in this paper. A short review is presented on the two basic types of foundations, i.e. monopiles and gravity foundations, including their basic features and applications as well as general design considerations. Also, some issues regarding analysis are discussed, including geotechnical problems and modelling techniques. A numerical model of offshores turbine...
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A simple and efficient hybrid discretization approach to alleviate membrane locking in isogeometric thin shells
PublicationThis work presents a new hybrid discretization approach to alleviate membrane locking in isogeometric finite element formulations for Kirchhoff–Love shells. The approach is simple, and requires no additional dofs and no static condensation. It does not increase the bandwidth of the tangent matrix and is effective for both linear and nonlinear problems. It combines isogeometric surface discretizations with classical Lagrange-based...
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Power control system structure of doubly‐fed induction generator connected to current source converter
PublicationThe power control system structures for a doubly-fed generator (DFIG) are proposed. The classical field oriented control and the feedback control with the multi-scalar variables were considered. The generator is working in the AC grid connection mode. The rotor side of the generator is connected to the current source converter (CSC); the stator is directly related to the AC grid. The static feedback linearization using the multi-scalar...
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Centrifuge modelling of tapered wall jacked into dense sand
PublicationA series of static penetration tests of trapezoidal walls in dense Fontainebleau sand were performed in the geotechnical centrifuge at Gustave Eiffel University. The models of wall with three different shapes (straight profile with thickness D=16mm, 0.75 degree and 1.5 degree of taper angle) but with the same volume were used. The soil mass was instrumented with five stress cells located at two levels at 2D, 4D and 6D distance...
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Sustainable development requires risky decisions - problematic 300 ton overweight transport passing a bridge
PublicationOversize load passages over bridges are one of the research issues related to sustainable development that engineering and scientific teams around the world have to deal with . The article presents the scope of activities that enabled the passage of an oversized vehicle with a total weight of over 300 tons over a reinforced concrete slab. The bridge load capacity is 30 tons. In order to assess the capacity of the bridge, detailed...
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Zastosowanie immobilizowanego białka MutS do wychwytywania fragmentów DNA zawierających niesparowane zasady
PublicationBiałko MutS wiąże DNA zawierające błędnie sparowane oraz niesparowane zasady w DNA. Podjęto szereg prób wykorzystania tego białka jako narzędzia do detekcji nieznanych mutacji lub zagęszczania frakcji DNA z niesparowaną zasadą. Dotychczas żadna z metod oparta na użyciu białka MutS nie została wdrożona powszechnie do praktyki laboratoryjnej. Głównym powodem takiego stanu rzeczy jest stosunkowo silne powinowactwo MutS do DNA w pełni...
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Selective Cytostatic and Cytotoxic Anticancer Effects of Bisfunctional Agents: A Strategy for the Design of DNA Binding Agents
PublicationVarious agents have been synthesized and proved useful for the National Cancer Institute's anticancer testing as potential new drugs, but most agents suffer side effects from their limited selectivity against cancer cells over healthy ones. Therefore, this paper attempts to describe drugs in terms of the level of tumor cell selectivity which they possess to define the features of mols. that are essential for useful cytotoxicity....
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Environmental fate of endocrine disrupting compounds - analytical problems and challenges
PublicationNarażenie na substancje wykazujące się aktywnością hormonów płciowych może negatywnie wpływać na układ endokrynny i rozrodczy u ludzi i innych organizmów żywych. Badania wykazały że obserwowane są znaczne wzrosty przypadków występowania nowotworów piersi, prostaty i jąder. Inne zaś wykazały obniżoną liczbę plemników w nasieniu mężczyzn i wydłużenie czasu oczekiwania na poczęcie. Odkrycia te znajdują potwierdzenie w badaniach polowych...
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Novel fused pyran derivatives induce apoptosis and target cell cycle progression in anticancer efficacy against multiple cell lines.
PublicationNitrogen-based heterocycles such as pyrazole, imidazole, 1,2,4-triazole, benzimidazole, and benzotriazole substituted fused pyran derivatives (6a–e, 8a–e, 10a–e, 12a–e,&14a–e) have been synthesized and tested for their in vitro anticancer efficacies against MCF7, A549, and HCT116 cancer cell lines. Among the compounds, 6e, 14b, and 8c were identified as the most potent against MCF7, A549, and HCT116, with IC50 values of 12.46 2.72...
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Biocompatibility and potential functionality of lanthanum-substituted cobalt ferrite spinels
PublicationBulk and nanostructurized lanthanum-cobalt spinels have attracted a lot of interest from researchers, due to their unique physical and chemical properties as well as functionalities, which are interesting for biomedical and electronic industries. In this manuscript we show that introducing small lanthanum (La3+) content can tune magnetic, electronic and cytotoxic properties of the CoFe2− xLaxO4 system (x ≤ 0.1). The mechanisms...
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Recent advances in 3D bioprinted tumor models for personalized medicine
PublicationCancerous tumors are among the most fatal diseases worldwide, claiming nearly 10 million lives in 2020. Due to their complex and dynamic nature, modeling tumors accurately is a challenging task. Current models suffer from inadequate translation between in vitro and in vivo results, primarily due to the isotropic nature of tumors and their microenvironment's relationship. To address these limitations, hydrogel-based 3D bioprinting...
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Evaluating the antibacterial activity of muramyl dipeptide derivatives, retro-tuftsin derivatives, and anthraquinone oligopeptides against a range of pathogenic bacteria
PublicationSearch for new and efficient antibiotic is crucial because of microbial drug resistance and problems with side effects of the administered medication. In this study, we evaluate the in vitro microbiological activity of muramyl dipeptide derivatives, retro-tuftsin derivatives (i.e., tuftsin with reversed amino acid sequences), and combinations of retro-tuftsin derivatives with substituted anthraquinones. The potency of the investigated...
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Assessment of the usefulness of bacterial cellulose produced by Gluconacetobacter xylinus E25 as a new biological implant
PublicationBionanocellulose (BNC) is a clear polymer produced by the bacterium Gluconacetobacter xylinus. In our current study, “Research on the use of bacterial nanocellulose (BNC) in regenerative medicine as a function of the biological implants in cardiac and vascular surgery”, we carried out material analysis, biochemical analysis, in vitro tests and in vivo animal model testing. In stage 1 of the project, we carried out physical and...
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Defining a novel domain that provides an essential contribution to site-specific interaction of Rep protein with DNA
PublicationAn essential feature of replication initiation proteins is their ability to bind to DNA. In this work, we describe a new domain that contributes to a replication initiator sequence-specific interaction with DNA. Applying biochemical assays and structure prediction methods coupled with DNA–protein crosslinking, mass spectrometry, and construction and analysis of mutant proteins, we identified that the replication initiator of the...
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Synthesis, molecular structure, and metabolic stability of new series of N' -(2-alkylthio-4-chloro-5-methylbenzenesulfonyl)-1-(5-phenyl-1 H -pyrazol-1-yl)amidine as potential anti-cancer agents
PublicationA series of new N'-(2-alkylthio-4-chloro-5-methylbenzenesulfonyl)-1-(5-phenyl-1H-pyrazol-1-yl)amidine derivatives have been synthesized and evaluated in vitro by MTT assays for their antiproliferative activity against cell lines of colon cancer HCT-116, cervical cancer HeLa and breast cancer MCF-7. The studied compounds display selective activity mainly against HCT-116 and HeLa cells. Thus, five compounds show selective cytotoxic...
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Antibacterial Activity and Cytocompatibility of Bone Cement Enriched with Antibiotic, Nanosilver, and Nanocopper for Bone Regeneration
PublicationBacterial infections due to bone replacement surgeries require modifications of bone cement with antibacterial components. This study aimed to investigate whether the incorporation of gentamicin or nanometals into bone cement may reduce and to what extent bacterial growth without the loss of overall cytocompatibility and adverse effects in vitro. The bone cement Cemex was used as the base material, modified either with gentamicin...
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OCENA UZIEMIEŃ SŁUPÓW LINII ELEKTROENERGETYCZNYCH ZWŁASZCZA POSADOWIONYCH NA GRUNTACH O WYSOKIEJ REZYSTYWNOŚCI
PublicationW artykule została omówiona problematyka pomiaru i oceny właściwości uziemień słupów linii elektroenergetycznych z wykorzystaniem przebiegów wolno-i szybkozmiennych. Uzyskanie odpowiednio niskiej wartości rezystancji uziemienia słupa posadowionego na gruncie o rezystywności powyżej 1000Ωm może być trudne. Praca zawiera analizę zmian właściwości statycznych i udarowych uziemień w funkcji rezystywności...
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Use of a wastewater recovery product (struvite) to enhance subtropical seagrass restoration
PublicationSeagrasses are in decline worldwide, and their restoration is relatively expensive and unsuccessful compared to other coastal systems. Fertilization can improve seagrass growth in restoration but can also release nutrients and pollute the surrounding ecosystem. A slow-release fertilizer may reduce excessive nutrient discharge while still providing resources to the seagrass's rhizosphere. In this study, struvite (magnesium ammonium...
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Dynamika bezzałogowego aparatu latającego w układzie czterowirnikowego pionowzlotu
PublicationDziałanie maszyn, w tym również pojazdów latających, jest nieodłącznie związane z przekazywaniem oddziaływań siłowych: statycznych i dynamicznych. Dynamika jest działem mechaniki zajmującym się makroskopowym ruchem ciał przy uwzględnieniu przyczyn wywołujących ten ruch. Pierwszym etapem analizy dynamiki konstrukcji są zwykle obliczenia wartości i postaci drgań własnych modelu konstrukcji. Drgania własne zwykle ulegają szybkiemu...
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Investigation of stability and limit load of a truss overhead opened bridge
PublicationThe paper presents selected methods of determining stability and limit load of a truss top chord in opened bridges. These methods include linear buckling and non-linear static analysis based on the finite element method and algorithms based on design code procedures. The described methods were tested on an example of a steel footbridge situated in Straszyn. The results of stability analysis are compared. The results of geometrical...
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Wavepacket of the Universe and its Spreading
PublicationWavepackets in quantum mechanics spread and the Universe in cosmology expands. We discuss a formalism where the two effects can be unified. The basic assumption is that the Universe is determined by a unitarily evolving wavepacket defined on space-time. Space-time is static but the Universe is dynamic. Spreading analogous to expansion known from observational cosmology is obtained if one regards time evolution as a dynamical process...
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Testing OFDM Transmission Schemes for Shallow Water Acoustic Communications
PublicationLarge variability of communication properties of underwater acoustic channels, and especially strongly varying instantaneous conditions in shallow waters, is a tough challenge for the designers of underwater acoustics communication (UAC system. There is a need for developing adaptive signaling schemes that would dynamically optimize signal parameters in both physical and link layers of communication protocols. The orthogonal frequency...
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Thermo-mechanical reclaiming of ground tire rubber via extrusion at low temperature: Efficiency and limits
PublicationThermomechanical reclaiming of ground tire rubber (GTR) was performed at different temperatures (60, 120, and 180°C) using a co-rotating twin-screw extruder. Obtained samples were used in styrene-butadiene rubber (SBR) blends. As reference samples, SBR compounds containing untreated GTR were used. Curing characteristics, static and dynamic mechanical properties, and morphology of the obtained blends were determined. The results...
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Dynamic Research of Masonry Vault in a Technical Scale
PublicationThe paper presents preliminary results of dynamic tests of the masonry barrel vault in a technical scale. Experimental studies are intended to identify material properties of homogenized masonry vaults under dynamic loads. The aim of the work is to create numerical models to analyse vault’s dynamic response to dynamic loads in a simplest and accurate way. The process of building the vault in a technical scale is presented in the...
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Models of Structures in Didactics
PublicationThe final aim of teaching students subjects, such as structural mechanics, reinforced concrete, and steel structures is to teach them how structures work in a given building as well as to provide them with skills enabling them to calculate and design structures. The behavioral model of the structure, contrary to the architectural model, which focuses mainly on the external form of the building, shows workings from both the static...
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Balancing energy processes in turbine engines
PublicationThe article discusses the issue of balancing energy processes in turbine engines in operation in aeronautic and PDULQHSURSXOVLRQV\VWHPVZLWKWKHDLPWRDQDO\VHDQGHYDOXDWH EDVLFRSHUDWLQJSDUDPHWHUV7KH¿UVWSDUWSUHVHQWV the problem of enormous amounts of energy needed for driving fans and compressors of the largest contemporary turbofan engines commonly used in long-distance aviation. The amounts of the transmitted power and the effect RIÀRZSDUDPHWHUVDQGFRQVWUXFWLRQDOSURSHUWLHVRIWKHHQJLQHV RQWKHLUSHUIRUPDQFHDQGUHDOHI¿FLHQF\DUH evaluated....
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Developing a methodology for model tests of floating platforms in a towing tank of low depth
PublicationThe paper presents two ways to mooring model of semi-submersible platform for research in the small depth towing pool. The tested model was made in the likeness of 1:100 Thunder Horse platform moored in the Gulf of Mexico at a depth of 1,920 m. Its mooring system consisted of 16 semi-taut mooring lines (chain-wire-chain) spaced Star-shape and attached at the bottom to the suction piles. The tests were performed in the towing pool...
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GaAs ballistic and tunneling nanodevices for terahertz electronics and medical applications
PublicationPrzy użyciu selektywnej epitaksji warstw molekularnych (MLE) wytworzono w GaAs balistyczne i tunelowe tranzystory o indukcji elektrostatycznej (SIT), z kanałami w skali 10 nm. Szacowany czas przelotu elektronów jest krótszy od 2×10-14 s. Metoda MLE została również wykorzystana do wykonania diod generacyjnych TUNNETT działających w oparciu o czas przelotu i tunelowe wstrzykiwanie elektronów. Z użyciem diod TUNNETT wygenerowano częstotliwość...
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Technical diagnostics and monitoring of traction current collectors
PublicationNew evaluation methods of the technical condition of rolling stock current collectors are proposed in this paper. The method of automatic measurement of the pantograph static force characteristic, realized when the vehicle runs through the test section of the track with especially prepared overhead line height distribution, has been practically implemented by the Polish Railways. The method of testing the slipper spring suspension...
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User Orientation Detection in Relation to Antenna Geometry in Ultra-Wideband Wireless Body Area Networks Using Deep Learning
PublicationIn this paper, the issue of detecting a user’s position in relation to the antenna geometry in ultra-wideband (UWB) off-body wireless body area network (WBAN) communication using deep learning methods is presented. To measure the impulse response of the channel, a measurement stand consisting of EVB1000 devices and DW1000 radio modules was developed and indoor static measurement scenarios were performed. It was proven that for...
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Numerical investigations of discrete crack propagation in Montevideo splitting test using cohesive elements and real concrete micro-structure
PublicationThe paper is aimed at accurately predicting the discrete fracture process in concrete specimens under complex stress states in two dimensional (2D) simulations. Plain concrete specimens subjected to Montevideo splitting test (MVD) were used for consideration due to non-negligible shear stresses impact in this type of test. In order to reflect the heterogeneous nature of the concrete, the meso-structure of the samples was included...
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Numerical analysis on axial capacity of steel built-up battened columns
PublicationThis paper deals with the numerical analysis aimed at study the bearing capacity of pinended steel built-up columns under axial compression. Finite element (FE) models were performed for the columns presented in the literature. The main problem discussed in the article is the shape and magnitude of geometric imperfections introduced into the numerical FE model, necessary to obtain the load capacity consistent with the experimental...