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Wyszukujesz frazę "enclosure" wg kryterium: Temat

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    Wyświetlanie 1-5 z 5
    Tytuł:
    Estimation of solar radiation transmission for polycarbonate retractable swimming pool enclosures
    Autorzy:
    Zapałowicz, Zbigniew
    Garnysz-Rachtan, Agnieszka
    Powiązania:
    https://bibliotekanauki.pl/articles/1845493.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    outdoor swimming pool
    swimming pool roofing system
    pool enclosure
    polycarbonate enclosure
    solar transmission through enclosure
    Opis:
    Application of retractable enclosures enables to lengthen operation periods for outdoor swimming pools operated in the moderate climate zone. Enclosures allow to diminish energy losses from water in the pool to the environment. Thermal calculations for pools with retractable enclosures are difficult to carry out because of a number of required parameters which can only be estimated. One of them is the transmission of solar radiation through the enclosure. The present paper presents the method of estimation of this parameter for swimming pool enclosures made of polycarbonate panels that have multichannels structure. In order to calculate transmission, the methodology considering the multiples of solar reflection inside the enclosure and their absorption by polycarbonate has been elaborated. Calculation results for transmission of the enclosure were verified experimentally. Analysis of results show that the transmission depends strongly on the enclosure’s construction and on the direction of solar radiation on the enclosure. Mean transmission values of enclosure under research were determined both from calculations and experiment are equal to about 0.69 and 0.64, respectively. However, experimentally determined mean values of total transmission by parallel and perpendicular solar directions in relation to channel axes are equal to about 0.69 and 0.60, respectively.
    Źródło:
    Archives of Thermodynamics; 2021, 42, 1; 129-146
    1231-0956
    2083-6023
    Pojawia się w:
    Archives of Thermodynamics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sound-Absorbing and Insulating Enclosures for Ultrasonic Range
    Autorzy:
    Dobrucki, A.
    Żółtogórski, B.
    Pruchnicki, P.
    Bolejko, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/178036.pdf
    Data publikacji:
    2010
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    ultrasonic noise
    sound absorbing and insulating enclosure
    welder
    Opis:
    The physical phenomena occurring in sound-absorbing and insulating enclosures are subject of the present paper. These phenomena are: absorption in air and by the sound-absorbing material covering the walls and the coincidence effect. The absorption in the air can be neglected in small size enclosures for low ultrasonic frequencies (20–30 kHz). The coincidence plays a role in decrease of the sound insulation, however the main role play the leaks. The boards made of ceramic fibers have been chosen as the optimal sound-absorbing material. They are dense and have deeply porous structures. The enclosure for insulation of 20-kHz noise produced by a welding machine has been designed and manufactured, and reductions of 25 dB of peak and Leq levels have been achieved.
    Źródło:
    Archives of Acoustics; 2010, 35, 2; 157-164
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Double Panel Structure for Active Control of Noise Transmission
    Autorzy:
    Morzyński, L.
    Szczepański, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/176968.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    noise
    sound insulating enclosure
    active structural acoustic control
    virtual microphone
    Opis:
    Passive noise reduction means are commonly used to reduce noise in the industry but, unfortunately, their effectiveness is poor in the low frequency range. By applying active structural acoustic control to the enclosure walls significant improvement of the insulating properties in this frequency range can be achieved. In this paper a model of double panel structure with ASAC is presented. The structure consists of two aluminium plates separated by an air gap. Two inertial magnetoelectric actuators and two piezoceramic MFC sensors were used for controlling the structure. A multichannel FxLMS algorithm with virtual error microphone technique is used as a control algorithm. The signal of a virtual error microphone is extrapolated basing on signals from MFC sensors. Performance of this actively controlled structure for tonal signals at selected frequencies is presented in the article. During the study, a double panel structure was mounted on one wall of sound insulating enclosure located in an acoustic chamber. During the measurements local and global reduction of noise test signal was investigated.
    Źródło:
    Archives of Acoustics; 2018, 43, 4; 689-696
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Active Transient Acousto-Structural Response Control of a Smart Cavity-Coupled Circular Plate System
    Autorzy:
    Hasheminejad, S. M.
    Shakeri, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/176771.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    sound radiation
    structural-borne noise control
    coupled multi-field problem
    piezoelectric disc actuator
    cylindrical enclosure
    GA-tuned controller
    Opis:
    The transient vibroacoustic response suppression of a piezo-coupled sandwich circular plate backed by a rigid-walled cylindrical acoustic enclosure is investigated. Problem formulation is based on the linear acoustic wave theory, Kirchhoff thin plate model, fluid/structure compatibility relations, Rayleigh integra formula, and active damping control (ADC) strategy. Matlab’s Genetic Algorithm (GA) is utilized to identify and optimize the feedback controller gain parameter based on a multi-objective performance index function. Durbin’s numerical Laplace inversion scheme is then used to calculate the key acousto-structural response parameters due to a transverse impulsive shock force for selected cavity depths. Numerical simulations demonstrate satisfactory performance of adopted control methodology in effective suppression of panel displacement response and radiated external sound pressure for enclosures of shallow and moderate depths. Limiting cases are considered and accuracy of the proposed model is rigorously verified.
    Źródło:
    Archives of Acoustics; 2017, 42, 2; 273-286
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical study on the effects of multiple internal diathermal obstructions on natural convection in a fluid-saturated porous enclosure
    Autorzy:
    Chordiya, J. S.
    Sharma, R. V.
    Powiązania:
    https://bibliotekanauki.pl/articles/139520.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    thermal insulation
    natural convection
    internal obstructions
    porous enclosure
    Darcy's law
    izolacja termiczna
    konwekcja naturalna
    przeszkody wewnętrzne
    obudowa porowata
    prawo Darcy'ego
    Opis:
    The present work aims at studying the effects of orientation, size, position, and the combination of multiple internal diathermal obstructions in a fluid-saturated square porous enclosure, generally encountered in thermal insulations. The overall objective is to suppress the natural convection fluid flow and heat transfer across a differentially heated porous enclosure. To serve this purpose, multiple diathermal obstructions are employed to mechanically protrude into a porous medium. It is sought to estimate the effect of various types of orientation, clustering and alternate positioning of obstructions by considering number of obstructions (Np), length of obstructions (λ), modified Rayleigh number (Ra*) on local and average Nusselt number (Nu). The Darcy model for porous media is solved using Finite difference method along with Successive Accelerated Replacement scheme. One of the findings is that the value of the Nusselt number decreases by increasing both, the number of obstructions as well as the length of obstructions irrespective of its orientation and positioning. The reduction in Nusselt number is significant with obstructions attached on lower half of the hot wall and/or on upper half of cold wall. In addition, the overall reduction in Nusselt number is slightly greater with obstructions attached explicitly to the cold wall.
    Źródło:
    Archive of Mechanical Engineering; 2018, LXV, 4; 553-578
    0004-0738
    Pojawia się w:
    Archive of Mechanical Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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