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    Wyświetlanie 1-7 z 7
    Tytuł:
    Experimental investigation of a uniaxial dielectric elastomer generator
    Autorzy:
    Sikora, Wojciech
    Powiązania:
    https://bibliotekanauki.pl/articles/27314318.pdf
    Data publikacji:
    2023
    Wydawca:
    Politechnika Białostocka. Oficyna Wydawnicza Politechniki Białostockiej
    Tematy:
    dielectric elastomers
    energy harvester
    DEG
    uniaxial tension
    Opis:
    The widespread use of battery-powered electronic devices creates the need to develop methods to extend their maximum operating time. This can be achieved by using ambient energy, which would otherwise be dissipated. The conversion of energy, usually mechanical energy, into electric energy takes place in energy harvesters. Energy harvester systems based on a dielectric elastomer (DE) are a relatively new field that is being constantly developed. Due to their features, dielectric elastomer generators (DEGs) may complement the currently dominant piezoelectric harvesters. The major feature of employing a hyperelastic material is that it allows relatively large displacements to be utilised for generating energy, which is impossible in the case of piezoceramics. This article presents a DEG designed to operate under uniaxial tensile loads and which has a multilayer structure, describes the general operating principles of a DEG, explains the construction and assembly process of the investigated design and shows the electric circuit necessary to properly direct current flow during the DEG operation. The experimental part consists of two series of tests based on a central composite design (CCD). The objective of the first part was to map a capacitance response surface of the DEG in the selected range of the cyclic mechanical load. The second part concerned the amount of generated energy for the specific load case as a function of operating voltages. The result of the work is the formulation of regression models that allow the characteristics of the presented DEG design to be identified.
    Źródło:
    Acta Mechanica et Automatica; 2023, 17, 4; 499--506
    1898-4088
    2300-5319
    Pojawia się w:
    Acta Mechanica et Automatica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mechanical and Tribological Analysis of Monolith and Coating Polyetheretherketone
    Analiza właściwości mechanicznych i tribologicznych polieteroeteroketonu w postaci monolitycznej i powłoki
    Autorzy:
    Otto, Mateusz
    Zimowski, Sławomir
    Sikora, Wojciech
    Moskalewicz, Tomasz
    Powiązania:
    https://bibliotekanauki.pl/articles/188181.pdf
    Data publikacji:
    2019
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    PEEK
    twardość
    współczynnik tarcia
    wskaźnik zużycia objętościowego
    odporność na mikrouszkodzenia
    hardness
    coefficient of friction
    wear rate
    Micro Mar Resistance
    Opis:
    W pracy dokonano analizy porównawczej właściwości mikromechanicznych oraz tribologicznych polieteroeteroketonu (PEEK) w postaci monolitycznej i powłoki. Powłoka PEEK 708 została osadzona metodą elektroforezy na płaskim podłożu ze stopu tytanu. Właściwości mikromechaniczne zostały zbadane metodą indentacyjną przy użyciu wgłębnika Vickersa oraz w teście zarysowania. Na podstawie badań wyznaczono twardość Vickersa (HV), moduł sprężystości (E), twardość zarysowania (HS) oraz odporność na mikrouszkodzenia (MMR). Właściwości tribologiczne zdefiniowano poprzez współczynnik tarcia (fs i fw), który wyznaczono zarówno w teście zarysowania oraz podczas tarcia w układzie typu kula–tarcza. Wyniki badań wskazują, że pomimo niedużo większej twardości Vickers’a (HV) powłoki PEEK 708 (HV = 350 MPa, HS = 300 MPa) względem monolitycznego PEEK (HV = 300 MPa, HS = 210 MPa), występuje niemal 40% różnica w ich twardościach zarysowania (HS). Z przeprowadzonej analizy wynika, że metody wyznaczania parametrów mikromechanicznych oraz tribologicznych stosowane dla materiałów monolitycznych PEEK sprawdzają się w badaniach powłok polimerowych PEEK. W określonych warunkach badań nie stwierdzono wpływu materiału podłoża na otrzymane wyniki dla powłoki PEEK 708.
    In this work, a comparative analysis of the micromechanical and tribological properties of polyetheretherketone (PEEK) in bulk and coating form was performed. The PEEK 708 coating was applied on a Ti6Al4V titanium alloy flat specimen using the electrophoretic deposition method. The micromechanical properties were determined through indentation tests performed using the Vickers method and scratch tests. Based on research work, the Vickers hardness (HV), elastic modulus (E), scratch hardness (HS), and Micro Mar Resistance (MMR) were determined. The tribological properties were defined by the coefficient of friction (fs and fw), which was obtained in scratch tests and ball-on-disk tests. The results of this research indicate, despite the slightly higher Vickers hardness (HV) of the PEEK 708 coating (HV = 350 MPa, HS = 300 MPa) relative to PEEK bulk (HV = 300 MPa, HS = 210 MPa), that there is an almost 40% difference between the scratch hardness (HS) values of these PEEK forms. It appears from the result analysis in this paper that testing methods to determine the micromechanical and tribological properties of PEEK in monolith form can be used for both PEEK coatings. Under certain test conditions, the impact of the substrate properties on the results of the PEEK 708 coating was not found.
    Źródło:
    Tribologia; 2019, 286, 4; 73-86
    0208-7774
    Pojawia się w:
    Tribologia
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Equivalent parameters of metal-elastomer vibroinsulators
    Autorzy:
    Cieplok, Grzegorz
    Wójcik, Kaja
    Michalczyk, Krzysztof
    Sikora, Wojciech
    Powiązania:
    https://bibliotekanauki.pl/articles/2146556.pdf
    Data publikacji:
    2020
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    metal-elastomer vibroinsulators
    vibratory machines
    general motion
    wibroizolatory metalowo-elastomerowe
    maszyny wibracyjne
    ruch ogólny
    Opis:
    This paper concerns a substitute model of the metal-elastomer vibroinsulator that can find use in the mathematical description of vibration machine suspensions. In the case of a plane system, the flexibility matrix of the vibroinsulator was derived and two typical configurations of machine suspensions: symmetrical and asymmetrical, were analysed. For the case of a spatial motion, the elastic matrix of the vibroinsulator and the method of determining its elements was specified. Due to the non-linear character of the vibroinsulator's work, which is caused by large deformations of elastomeric elements under static loads, the analysis was limited to the surroundings of the work point and linear model. The results of theoretical analyses were confirmed by experimental tests.
    Źródło:
    Vibrations in Physical Systems; 2020, 31, 2; art. no. 2020204
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Physical and reliability aspects of high-pressure ammonia water pipeline failures
    Autorzy:
    Michnej, Maciej
    Młynarski, Stanisław
    Pilch, Robert
    Sikora, Wojciech
    Smolnik, Maksymilian
    Drożyner, Przemysław
    Powiązania:
    https://bibliotekanauki.pl/articles/2200924.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Polskie Naukowo-Techniczne Towarzystwo Eksploatacyjne PAN
    Tematy:
    coke oven battery
    pipeline
    welded joint
    crack
    structural analysis
    reliability assessment
    Opis:
    The paper concerns the problem of the occurrence of failures of the high-pressure ammonia water pipeline of the coke oven battery complex, which is affected by chemical and thermal factors as well as the operating pressure occurring during its use. Pipeline failures manifested themselves as leaks (leakage of the medium) due to cracks in the area of the pipeline thermal elongation compensators. The conducted tests included, among others: visual inspection, penetration tests, macroscopic and microscopic tests as well as chemical analysis of the material. The study includes microscopic photographs of the material structure and cracks. The results of the pipeline strength and reliability analysis were also presented. On the basis of the conducted research and analyses conclusions were formulated. The assumed cause of the damage was the incorrectly made welded joints. Formulated recommendations and proposals for actions aimed at avoiding further failures of this and similar pipelines were related to the inspection time and preventive renewal.
    Źródło:
    Eksploatacja i Niezawodność; 2022, 24, 4; 728--737
    1507-2711
    Pojawia się w:
    Eksploatacja i Niezawodność
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of the changes to land use in selected municipalities of Lublin metropolitan area, based on remote sensing data
    Autorzy:
    Kwoczyńska, Bogusława
    Sroka, Wojciech
    Sikora, Kamila
    Powiązania:
    https://bibliotekanauki.pl/articles/100440.pdf
    Data publikacji:
    2019
    Wydawca:
    Uniwersytet Rolniczy im. Hugona Kołłątaja w Krakowie
    Tematy:
    satellite imagery
    land cover
    metropolitan area
    MA
    zdjęcie satelitarne
    pokrycie terenu
    obszar metropolitalny
    Opis:
    The aim of the study was to diagnose the main trends of the changes in land cover around the urban agglomerations, as illustrated with the example of Lublin, over the last twenty years (1998–2016), as well as their statistical and graphical presentation in the form of digital maps compilation. The project was conducted on the basis of the remote sensing data: RapidEye and LANDSAT 5 TM satellite imagery from three temporal records (1998, 2009–11, 2016–17). Detailed research was carried out in purposefully selected municipalities. The performed analyses showed that in the studied municipalities some changes in the use of arable land and grassland occurred. The largest loss in terms of area share was recorded mainly in the arable land. At the core of the metropolitan area, i.e. in the city of Lublin, over the last 20 years the share of arable land in the total area decreased by almost 11 percentage points (p.p.). In the municipalities located directly at the border with Lublin, this loss was much lower, and was equal 4–5 p.p. Slightly larger changes occurred in municipalities located further from the core, where both in the category of very good and slightly weaker natural conditions, losses of arable land were greater than in municipalities located directly at the core’s border of the metropolitan area (MA).
    Źródło:
    Geomatics, Landmanagement and Landscape; 2019, 4; 73-91
    2300-1496
    Pojawia się w:
    Geomatics, Landmanagement and Landscape
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Altered mouse leukemia L1210 thymidylate synthase, associated with cell resistance to 5-fluoro-dUrd, is not mutated but rather reflects posttranslational modification
    Autorzy:
    Cieśla, Joanna
    Frączyk, Tomasz
    Zieliński, Zbigniew
    Sikora, Jacek
    Rode, Wojciech
    Powiązania:
    https://bibliotekanauki.pl/articles/1041288.pdf
    Data publikacji:
    2006
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    protein phosphorylation
    L1210
    thymidylate synthase
    posttranslational modification
    FdUrd resistance
    Opis:
    Thymidylate synthase purified from 5-fluoro-dUrd-resistant mouse leukemia L1210 cells (TSr) was less sensitive to slow-binding inhibition by 5-fluoro-dUMP than the enzyme from the parental cells (TSp), both enzyme forms differing also in sensitivity to several other dump analogues, apparent molecular weights of monomer and dimer, and temperature dependence of the catalyzed reaction. Direct sequencing of products obtained from RT-PCR, performed on total RNA isolated from the parental and 5-fluoro-dUrd-resistant cells, proved both nucleotide sequences to be identical to the mouse thymidylate synthase coding sequence published earlier (NCBI protein database access no. NP_067263). This suggests that the altered properties of TSr are caused by a factor different than protein mutation, presumably posttranslational modification. As a possibility of rat thymidylate synthase phosphorylation has been recently demonstrated (Samsonoff et al. (1997) J Biol Chem 272: 13281), the mouse enzyme amino-acid sequence was analysed, revealing several potential phosphorylation sites. In order to test possible influence of the protein phosphorylation state on enzymatic properties, endogenous TSp and TSr were purified in the presence of inhibitors of phosphatases. Although both enzyme forms were phosphorylated, as shown by electrophoretical separation followed by phosphoprotein detection, the extent of phosphorylation was apparently similar. However, the same two purified enzyme preparations, compared to the corresponding preparations purified in the absence of phosphatase inhibitors, showed certain properties, including sensitivity to the slow-binding inhibition by FdUMP, altered. Thus properties dependence on phosphorylation was indicated.
    Źródło:
    Acta Biochimica Polonica; 2006, 53, 1; 189-198
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Physico-chemical and rheological properties of gelatinized/freeze-dried cereal starches
    Autorzy:
    Krystyjan, Magdalena
    Ciesielski, Wojciech
    Gumul, Dorota
    Buksa, Krzysztof
    Ziobro, Rafał
    Sikora, Marek
    Powiązania:
    https://bibliotekanauki.pl/articles/972985.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Instytut Agrofizyki PAN
    Tematy:
    cereal starch
    gelatinization
    freeze-drying
    process
    Opis:
    The influence of gelatinization and freeze-drying process on the physico-chemical and rheological properties of cereal starches was evaluated, and it was observed that modified starches revealed an increased water binding capacity and solubility when compared to dry starches, while exhibiting the same amylose and fat contents. The molecular weights of starches decreased after modification which resulted in the lower viscosity of dissolved modified samples in comparison to native starch pastes. As it was observed by scanning electron microscopy modified starches were characterized by an expanded surface, a uniform structure and high porosity.
    Źródło:
    International Agrophysics; 2017, 31, 3; 357-365
    0236-8722
    Pojawia się w:
    International Agrophysics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-7 z 7

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