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    Wyświetlanie 1-6 z 6
    Tytuł:
    Impact of mesh quality on the numerical estimation of saturated water conductivity of pore media
    Autorzy:
    Gackiewicz, B.
    Lamorski, K.
    Slawiński, C.
    Hsu, S.-Y.
    Chang, L.-C.
    Powiązania:
    https://bibliotekanauki.pl/articles/2082923.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Instytut Agrofizyki PAN
    Tematy:
    porous media
    numerical modelling
    hydraulic
    conductivity
    mesh accuracy
    Opis:
    The numerical modelling of transport phenomena in porous media often requires a compromise between grid precision and the accuracy of simulation results. This study demonstrates the impact of errors on the accuracy of the reproduction of the actual pore space by the numerical grid on the estimated values of the saturated water conductivity. Four types of computational grids with varying levels of complexity were prepared for each of the 12 tomographic images of the porous specimens. The specific surfaces and total porosities were calculated for each of the meshes and compared with those parameters calculated for binarized tomographic images. Simulations of steady flow were performed on the computational grids, and the saturated water conductivity values were calculated. It has been shown that an insufficiently accurate mesh only reproduces the largest pore spaces in the analysed sample, which most often leads to an underestimation of the water conductivity coefficient. The following criterion for the optimal accuracy of the computational grid is proposed, it is based on the voxel size of the tomographic images of the porous media: the minimum size of the cell in the mesh used for simulations has to be at most two times the size of the voxel used in the tomographic scans of the porous medium.
    Źródło:
    International Agrophysics; 2020, 34, 4; 473-483
    0236-8722
    Pojawia się w:
    International Agrophysics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Noise Elimination of Reciprocating Compressors Using FEM, Neural Networks Method, and the GA Method
    Autorzy:
    Chang, Y.-C.
    Chiu, M.-C.
    Xie, J.-L.
    Powiązania:
    https://bibliotekanauki.pl/articles/178126.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    finite element method
    polynomial neural network model
    genetic algorithm
    group method of data handling
    reciprocating compressor
    optimization
    Opis:
    Industry often utilizes acoustical hoods to block noise emitted from reciprocating compressors. However, the hoods are large and bulky. Therefore, to diminish the size of the compressor, a compact discharge muffler linked to the compressor outlet is considered. Because the geometry of a reciprocating compressor is irregular, COMSOL, a finite element analysis software, is adopted. In order to explore the acoustical performance, a mathematical model is established using a finite element method via the COMSOL commercialized package. Additionally, to facilitate the shape optimization of the muffler, a polynomial neural network model is adopted to serve as an objective function; also, a Genetic Algorithm (GA) is linked to the OBJ function. During the optimization, various noise abatement strategies such as a reverse expansion chamber at the outlet of the discharge muffler and an inner extended tube inside the discharge muffler, will be assessed by using the artificial neural network in conjunction with the GA optimizer. Consequently, the discharge muffler that is optimally shaped will decrease the noise of the reciprocating compressor.
    Źródło:
    Archives of Acoustics; 2017, 42, 2; 189-197
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical Assessment of a One-Mass Spring-Based Electromagnetic Energy Harvester on a Vibrating Object
    Autorzy:
    Chiu, M.-C.
    Chang, Y.-C.
    Yeh, L.-J.
    Chung, C.-H.
    Powiązania:
    https://bibliotekanauki.pl/articles/177720.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    spring
    harvester
    generator
    permanent magnet
    simulated annealing
    optimization
    buckling
    Fatigue
    Opis:
    The paper is an exploration of the optimal design parameters of a space-constrained electromagnetic vibration-based generator. An electromagnetic energy harvester is composed of a coiled polyoxymethylen circular shell, a cylindrical NdFeB magnet, and a pair of helical springs. The magnet is vertically confined between the helical springs that serve as a vibrator. The electrical power connected to the coil is actuated when the energy harvester is vibrated by an external force causing the vibrator to periodically move through the coil. The primary factors of the electrical power generated from the energy harvester include a magnet, a spring, a coil, an excited frequency, an excited amplitude, and a design space. In order to obtain maximal electrical power during the excitation period, it is necessary to set the system’s natural frequency equal to the external forcing frequency. There are ten design factors of the energy harvester including the magnet diameter (Dm), the magnet height (Hm), the system damping ratio (ζsys), the spring diameter (Ds), the diameter of the spring wire (ds), the spring length (ℓs), the pitch of the spring (ps), the spring’s number of revolutions (Ns), the coil diameter (Dc), the diameter of the coil wire (dc), and the coil’s number of revolutions (Nc). Because of the mutual effects of the above factors, searching for the appropriate design parameters within a constrained space is complicated. Concerning their geometric allocation, the above ten design parameters are reduced to four (Dm, Hm, ζsys, and Nc). In order to search for optimal electrical power, the objective function of the electrical power is maximized by adjusting the four design parameters (Dm, Hm, ζsys, and Nc) via the simulated annealing method. Consequently, the optimal design parameters of Dm, Hm, ζsys, and Nc that produce maximum electrical power for an electromagnetic energy harvester are found.
    Źródło:
    Archives of Acoustics; 2016, 41, 1; 119-131
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Acid alpha-galactosidase is involved in D-chiro-inositol accumulation during tartary buckwheat germination
    Autorzy:
    Jia, C.-F.
    Hu, W.-H.
    Chang, Z.
    Gao, H.-L.
    Powiązania:
    https://bibliotekanauki.pl/articles/59199.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Botaniczne
    Tematy:
    alpha-galactosidase
    D-chiro-inositol
    accumulation
    tartary buckwheat
    Fagopyrum tataricum
    duckwheat zob.tartary buckwheat
    India buckwheat zob.tartary buckwheat
    India wheat zob.tartary buckwheat
    green buckwheat zob.tartary buckwheat
    germination
    gene expression
    Opis:
    Tartary buckwheat seed and especially its sprouts are rich in D-chiroinositol (DCI). The research was to evaluate when DCI was most accumulated in tartary buckwheat sprouts. In addition, we explored the activity and expression pattern of α-galactosidase during tartary buckwheat seed germination. The results showed that DCI contents steadily increased at early stage of germination and reached the highest level of 33.42 μg/seed at 24 h during the 72 h trail. However, the total fagopyritol contents sharply decreased from 214.6 μg/seed to 46 μg/seed at the end of the germination. The activity of acid α-galactosidase increased gradually to the peak of 0.36 nkat/seed at 24 h after the primed seed imbibition. We cloned the gene fragment of α-galactosidase in tartary buckwheat for the first time. The deduced amino acid sequence is 93% identical to that of P. vulgaris. The quantitative PCR result of gene expression pattern was consistent with its enzyme activity during seed germination.
    Źródło:
    Acta Societatis Botanicorum Poloniae; 2015, 84, 1
    0001-6977
    2083-9480
    Pojawia się w:
    Acta Societatis Botanicorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of Vacuum Hot-Press Process on The Sintered Characteristics and Mechanical Properties of A High-Density Cr-31.2 Mass% Ti Alloy
    Autorzy:
    Chang, S.-H.
    Li, C.-L.
    Huang, K.-T.
    Yang, T.-H.
    Powiązania:
    https://bibliotekanauki.pl/articles/356911.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Cr-31.2 mass% Ti alloy
    vacuum hot-press sintering
    relative density
    TRS
    electrical conductivity
    Opis:
    In this study, two different compositions of submicron-structured titanium (760 nm) and micron-structured chromium (4.66 μm) powders were mixed to fabricate Cr-31.2 mass% Ti alloys by vacuum hot-press sintering. The research imposed various hot-press sintering pressures (20, 35 and 50 MPa), while the sintering temperature maintained at 1250°C for 1h. The experimental results showed that the optimum parameters of the hot-press sintered Cr-31.2 mass% Ti alloys were 1250°C at 50 MPa for 1h. Also, the relative density reached 99.94%, the closed porosity decreased to 0.04% and the hardness and transverse rupture strength (TRS) values increased to 81.90 HRA and 448.53 MPa, respectively. Moreover, the electrical conductivity is enhanced to 1.58 × 104 S·cm-1 However, the grain growth generated during the high-temperature and high-pressure of the hot-press sintering process resulted in the grain coarsening phenomenon of the Cr-31.2 mass% Ti alloys after 1250°C hot-press sintering at 50 MPa for 1h. In addition, the Cr-31.2 mass% Ti alloys were fabricated with the submicron-structured titanium (760 nm) and chromium (588 nm) powders showed more effective compaction than the micron-structured titanium (760 nm) and chromium (4.66 μm) powders did. The closed porosity decreases to 0.02% and the hardness values increase to 83.23 HRA. However, the agglomeration phenomenon of the Cr phase and brittleness of the TiCr2 Laves phases easily led to a slight decrease in TRS (400.54 MPa).
    Źródło:
    Archives of Metallurgy and Materials; 2018, 63, 4; 1715-1723
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Finite element analysis of three-point bending of a T-beam structural biaxial highly oriented polymer material
    Analiza metodą elementów skończonych zginania trójpunktowego belki teowej wykonanej z wysoko zorientowanego dwuosiowo materiału polimerowego
    Autorzy:
    Wei, C.-L.
    Chang, Y.
    Lee, Y.-C.
    Lee, R.
    Luo, T.-W.
    Chen, J.-H.
    Powiązania:
    https://bibliotekanauki.pl/articles/946988.pdf
    Data publikacji:
    2018
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Chemii Przemysłowej
    Tematy:
    solid phase processing
    highly oriented polymer (HOP)
    orthotropic materials
    T-beam
    three-point bending
    finite element
    proces w fazie stałej
    wysoko zorientowany polimer
    materiały ortotropowe
    belka teowa
    zginanie trójpunktowe
    elementy skończone
    Opis:
    Polymers with biaxial aligned molecular chains are also orthotropic materials, which are characterized by high tensile strength and low shear strength in the length direction. When orthotropic materials are used as structural shapes with poor shear strength, they are likely to undergo premature failure under shear stress. Therefore, in three-point bending, the cross-section of the entire profile not only bears tensile stress and compressive stress in the length direction, but also simultaneously exhibits shear stress. This study analyzes the distribution of tensile stress, compressive stress and shear stress in the length direction of highly oriented polymers (HOP) by finite element analysis to find the most suitable length-to-height ratio for these materials when used as structural shapes. The finite element analysis software, Abaqus, is utilized to simulate HOP T-beam to analyze the load stress of a T-beam. With a fixed cross–section area, as the length of the material changes, its shear strength also changes. Accordingly, the order of occurrence of tensile failure and shear failure can be investigated. The simulation reveals that when the length-to-height ratio is between 4 : 1 and 20 : 1, a zone of stress in which tensile failure and shear failure occur can be found. This result can be exploited in the design and development of structural beam.
    Polimery o dwuosiowo zorientowanych łańcuchach makrocząsteczek są materiałami ortotropowymi, wykazującymi dużą wytrzymałość na rozciąganie oraz niewielką wytrzymałość na ścinanie w kierunku długości. Elementy konstrukcyjne wytworzone z materiału ortotropowego o małej wytrzymałości na ścinanie są podatne na przedwczesne uszkodzenie pod wpływem naprężeń ścinających. Przy zginaniu trójpunktowym w przekroju ich profilu występują zarówno naprężenia rozciągające i ściskające w kierunku podłużnym, jak i naprężenia ścinające. Metodą elementów skończonych analizowano rozkład naprężeń rozciągających, ściskających i ścinających w kierunku podłużnym wysoko zorientowanych polimerów (HOP) w celu określenia optymalnego stosunku długości do wysokości w kształtach konstrukcyjnych. Do symulacji naprężeń obciążeniowych w zginaniu trójpunktowym belki teowej wykorzystano program komputerowy Abaqus. Stwierdzono, że przy stałej powierzchni przekroju poprzecznego belki jej wytrzymałość na ścinanie zmienia się wraz ze zmianą długości. Badano również kolejność występowania uszkodzeń pod wpływem działania sił rozciągających i ścinających. Symulacja wykazała, że przy stosunku długości do wysokości w zakresie od 4 : 1 do 20 : 1 występuje strefa naprężeń, w której mogą się pojawiać uszkodzenia w wyniku rozciągania lub ścinania. Uzyskane wyniki można wykorzystać w projektowaniu i optymalizacji belek konstrukcyjnych.
    Źródło:
    Polimery; 2018, 63, 3; 219-223
    0032-2725
    Pojawia się w:
    Polimery
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-6 z 6

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