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    Wyświetlanie 1-7 z 7
    Tytuł:
    Dynamic properties of hot-wire anemometric measurement circuits in the aspect of measurements in mine conditions
    Właściwości dynamiczne termoanemometrycznych układów pomiarowych w aspekcie pomiarów w warunkach kopalnianych
    Autorzy:
    Jamróz, P.
    Ligęza, P.
    Socha, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/219896.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    pomiary zjawisk przepływowych
    pasmo przenoszenia
    częstotliwość graniczna
    termoanemometryczne układy pomiarowe
    measurements of flow phenomena
    transmission band
    limiting frequency
    hot-wire anemometric measurement systems
    Opis:
    The use of measurement apparatus under conditions which differ significantly from those under which the apparatus was adjusted carries the risk of altering the previously determined measurement characteristics. This is of special concern in the case of apparatus which is sensitive to external measurement conditions. Advanced measurement systems are equipped with algorithms which allow the negative effect of unstable environmental conditions on their static characteristics to be compensated for. Meanwhile, the problem of altered dynamic properties of such systems is often neglected. This paper presents a model study in which the effect of variable operational conditions on dynamic response of hot-wire anemometric measurement system in the case of simulated mine flows was investigated. A mathematical model of measurement system able to compensate the negative effect of changes in flow velocity and configuration of measurement apparatus itself on its dynamic properties was developed and investigated. Based on conducted experiments, we have developed an automatic regulation algorithm enabling the transmission band of measurement apparatus to be optimized for measurement conditions prevailing in mine environment.
    Stosowanie aparatury pomiarowej w warunkach różnych od warunków, w których aparatura ta była adjustowana niesie ze sobą ryzyko zmian wyznaczonych wcześniej charakterystyk pomiarowych. Dotyczy to w szczególności aparatury wrażliwej na zewnętrzne czynniki pomiarowe. Zaawansowane systemy pomiarowe wyposaża się w algorytmy pozwalające na kompensację negatywnego oddziaływania zmiennych warunków środowiskowych głównie na charakterystyki statyczne. Pomija się często przy tym problem zmian właściwości dynamicznych systemów. W artykule przedstawiono modelowe badania wpływu zmiennych warunków użytkowania na odpowiedź dynamiczną termoanemometrycznego systemu pomiarowego w warunkach pomiarów symulowanych przepływów kopalnianych. Opracowano i przebadano symulacyjnie matematyczny model układu pomiarowego zdolnego do kompensacji negatywnego wpływu zmian prędkości przepływu oraz konfiguracji aparatury pomiarowej na jej właściwości dynamiczne. Na podstawie przeprowadzonych badań stworzono algorytm automatycznej regulacji pozwalający na optymalizację pasma przenoszenia aparatury pomiarowej w warunkach pomiarów w środowisku kopalnianym.
    Źródło:
    Archives of Mining Sciences; 2012, 57, 3; 699-714
    0860-7001
    Pojawia się w:
    Archives of Mining Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Bandgap properties in locally resonant phononic crystal double panel structures with periodically attached pillars
    Autorzy:
    Qian, D.
    Shi, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/280927.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    bandgap property
    phononic crystal double panel
    band structure
    displacement field
    transmission power spectrum
    Opis:
    The locally resonant (LR) phononic crystal double panel structure made of a two-dimensional periodic array of a two-component cylindrical LR pillar connected between the upper and lower plates is proposed, and the bandgap properties of the structure are investigated theoretically in this paper. The band structures, displacement fields of eigenmodes and transmission power spectrums of the corresponding 8×8 finite structure are calculated by the finite element method. Numerical results and further analysis demonstrate that a band gap with a low starting frequency and a wide band width is opened by the coupling between dominant vibrations of the pillars and plate modes of the upper and lower plates when the vibration source and the receiver are considered on different sides of the structure. By comparing the band structures and displacement fields of the double panel and those of the single plate with the same parameters, many common characteristics are displayed. Then, the influence of geometrical parameters on the band gap are studied and understood with the help of a simple ‘spring-mass’ model.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2017, 55, 4; 1167-1179
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Performance analysis of dual-band microbolometer camera for industrial gases detection
    Autorzy:
    Więcek, P.
    Więcek, B.
    Powiązania:
    https://bibliotekanauki.pl/articles/114214.pdf
    Data publikacji:
    2018
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    wide-band microbolometer detector
    IR spectral transmission and absorption
    configuration factors
    IR absorption of methane
    Opis:
    In this paper we present a simplified performance analysis of wide-band microbolometer cameras for gas detection. The spectral characteristics of camera’s elements such as detector, lens and filter were considered in this analysis. The parasitic radiation of IR filter that diminishes the contrast was included in the model. The exemplary results are presented for methane detection both in MWIR and LWIR bands of absorption
    Źródło:
    Measurement Automation Monitoring; 2018, 64, 4; 90-94
    2450-2855
    Pojawia się w:
    Measurement Automation Monitoring
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wave Propagation in a LRPC Composite Double Panel Structure with Periodically Attached Pillars and Etched Holes
    Autorzy:
    Qian, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/176620.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    locally resonant phononic crystal
    composite double panel structure
    band structure
    displacement field
    transmission power spectrum
    “base-spring-mass” simplified model
    Opis:
    The locally resonant phononic crystal (LRPC) composite double panel structure (DPS) made of a twodimensional periodic array of a two-component cylindrical LR pillar connected between the upper and lower composite plates is proposed. The plates are composed of two kinds of materials and periodically etched holes. In order to reveal the bandgap properties of structure theoretically, the band structures, displacement fields of eigenmodes and transmission power spectrums of corresponding 8 × 8 finite structure are calculated and displayed by using finite element method (FEM). Numerical results and further analysis demonstrate that if the excitation and response points are picked on different sides of the structure, a wide band gap with low starting frequency is opened, which can be treated as the coupling between dominant vibrations of pillars and plate modes. In addition, the influences of filled-in rubber, etched hole and viscidity of soft material on band gap are studied and understood with the help of “base-spring-mass” simplified model.
    Źródło:
    Archives of Acoustics; 2018, 43, 4; 717-725
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Narrow transmission mode in one-dimensional symmetric defective photonic crystal containing metamaterial and high Tc superconductor
    Autorzy:
    Srivastava, Sanjeev K.
    Aghajamali, Alireza
    Powiązania:
    https://bibliotekanauki.pl/articles/173630.pdf
    Data publikacji:
    2019
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    photonic crystal
    photonic band gap
    transmission spectra
    transmission mode
    defect mode
    metamaterial
    negative index material
    superconductor photonic crystal
    Opis:
    We theoretically investigate the properties of narrow transmission mode (defect mode) within the reflection band in one-dimensional symmetric defective photonic crystal containing double negative metamaterial and high temperature superconductors. The transmittance spectrum of the proposed structure is obtained by using the characteristic or transfer matrix method. The results show that by increasing the thickness of air defect, transmission mode shifts towards the lower frequency side. But when the thickness of a superconductor layer is increased, transmission mode shifts towards the high frequency side. Further, the effect of temperature variation of superconducting defect on the defect mode has been investigated and found that when the temperature of superconducting layer increases the frequency of defect mode is red shifted. The shift in frequency has smaller value in the lower temperature region than in the higher temperature region, even if the change in temperature is same. Finally we have discussed the effect of variation of thickness on the defect mode by using the double negative metamaterial as defect layer in place of superconductor layer. The result shows that we get two modes for smaller thickness of double negative layer but only a single mode for larger thickness.
    Źródło:
    Optica Applicata; 2019, 49, 1; 37-50
    0078-5466
    1899-7015
    Pojawia się w:
    Optica Applicata
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mechanisms of plastic deformation in light high-manganese steel of TRIPLEX type
    Autorzy:
    Sozańska-Jędrasik, Liwia
    Borek, Wojciech
    Mazurkiewicz, Janusz
    Powiązania:
    https://bibliotekanauki.pl/articles/2090674.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Fe-Mn-Al-C steels
    mechanism of plastic deformation
    microbands
    shear bands
    slip band
    TEM
    transmission electron microscopy
    stale Fe-Mn-Al-C
    mechanizm odkształcenia plastycznego
    transmisyjna mikroskopia elektronowa
    pasmo ścinania
    mikropasma
    pasmo poślizgu
    Opis:
    In this scientific publication, research results of two newly developed hot-rolled Fe-Mn-Al-C (X105) and Fe-Mn-Al-Nb-Ti-C (X98) types of steel were compared. These types of steel are characterized by an average density of 6.68 g/cm³, a value 15% lower compared to conventional structural steel. Hot rolling was carried out on a semi-industrial line to evaluate the effect of hot plastic deformation conditions with different cooling variants on the structure. The detailed analysis of phase composition as well as microstructure allows us to state that the investigated steel is characterized by an austenitic-ferritic structure with carbides precipitates. The results of the transmission electron microscopy (TEM) tests of both types of steel after hot rolling showed the occurrence of various deformation effects such as shear bands, micro bands, and lens twins in the microstructure. Based on the research undertaken with the use of transmission electron microscopy, it was found that the hardening mechanism of the X98 and X105 steel is deformation-induced plasticity by the formation of shear bands (SIP) and micro shear bands (MBIP).
    Źródło:
    Bulletin of the Polish Academy of Sciences. Technical Sciences; 2021, 69, 5; e137412, 1--7
    0239-7528
    Pojawia się w:
    Bulletin of the Polish Academy of Sciences. Technical Sciences
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Design and Performance Analysis of a Tripleband Rectangular Slot Microstrip Patch Antenna for Wi-Fi, Wi-MAX and Satellite Applications
    Autorzy:
    Hossain, Md. Biplop
    Hossain, Md. Faruque
    Powiązania:
    https://bibliotekanauki.pl/articles/2055262.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    wireless communication
    triple band antenna
    gain
    directivity
    transmission power
    link budget
    Opis:
    A triple-band microstrip patch antenna is presented in this article with detail investigation of its working mechanism and performance characteristics. The antenna consists of a rectangular slot on the patch to achieve multiband operation. Three distinct frequencies of 2.4 GHz, 5.5 GHz and 7.5 GHz are achieved with return losses of 27 dB, 29 dB and 29 dB respectively. The Impedance Bandwidths are 70 MHz (2.52 GHz-2.44 GHz) at 2.4 GHz, 220 MHz (5.65 GHz-5.43 GHz) at 5.5 GHz and 250 MHz (7.57 GHz-7.32 GHz) at 7.5 GHz, which satisfy the requirements of Wi-Fi, Wi-MAX and satellite communications bands. The fabricated prototype of the antenna has total dimension of 53×53×1.6 mm³ over FR4 substrate. The antenna is simple and has sensible radiation characteristics with considerable gain. This work also focuses on developing a Link Budget model for its application in satellite communication. Most notably, it examines overall system efficiency and optimum path loss, distance analysis, system noise temperature, signal to noise power ratio, the size of antenna and the overall customer satisfactions. The highest gain of the antenna is achieved as 3.5 dB in the band (5.65 GHz-5.43 GHz), while the highest directivity and bandwidth are found as 8.7 dBi and 250 MHz respectively in the higher operating band. The affordable agreement between the simulated and measuring outcomes justifies that the antenna is often applicable for Wi-Fi (2.4 GHz), Wi-MAX (5.25 – 5.85 GHz) and satellite (7.24 – 7.57 GHz) communications.
    Źródło:
    International Journal of Electronics and Telecommunications; 2022, 68, 2; 217--222
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-7 z 7

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