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    Wyświetlanie 1-13 z 13
    Tytuł:
    Interaction of elastic waves with a fluid-saturated porous solid boundary
    Oddziaływanie fal sprężystych z brzegiem nasyconego płynem ośrodka porowatego
    Autorzy:
    Cieszko, M.
    Kubik, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/281300.pdf
    Data publikacji:
    1998
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    saturated porous solids
    wave reflection
    Opis:
    The problem of energy reflection and transmission of an oblique incident plane harmonic wave at the surface of an elastic porous solid halfspace immersed in fluid is considered. The case of pure elastic behaviour of the system with incompressible material of skelton is analysed. Considerations are based on the two parametric theory of fluid-saturated porous solid in which the isotropic pore structure is described by the volume porosity and the parameter characterising tortuosity of pores. The influence of mechanical properties of both the physical constituents and angle of wave incidence on the energy reflection and transmission coefficients is analysed. Two general cases of the wave interaction are investigated: waves incident from the bulk fluid on the surface of porous halfspace, and waves (fast, slow and shear) incident from a fluid-saturated porous solid. Calculations have been made for the system composed of porous fused glass bead solid filled with water in one case and with ethyl alcohol in the other case and diagrams of the results have been shown.
    W pracy rozważono zagadnienie odbicia i przenikania fal harmonicznych ukośnie padających na powierzchnię porowatej półprzestrzeni zanurzonej w płynie. Przeanalizowano czysto sprężyste zachowanie się układu o nieściśliwym materiale szkieletu. Do rozważań wykorzystano dwuparametrową teorię deformowalnego ośrodka porowatego nasyconego płynem, w której struktura porów szkieletu charakteryzowana jest przez porowatość objętościową i krętość porów. Przeanalizowano wpływ mechanicznych własności składników fizycznych oraz kąt padania fali na energetyczne współczynniki odbicia i przenikania fal. Rozważono dwa przypadki: gdy fala pada na powierzchnię porowatej półprzestrzeni od strony samego płynu oraz przypadek, gdy fale (szybka, wolna i poprzeczna) padają od strony nasyconego płynem porowatego ośrodka. Obliczenia przeprowadzono dla ośrodka porowatego ze spiekanych kulek szklanych wypełnionych wodą w jednym przypadku oraz alkoholem etylowym w drugim przypadku.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 1998, 3; 561-580
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Pulse wave propagation along human aorta: a model study
    Autorzy:
    Kizilova, Natalya
    Mizerski, Jeremi
    Solovyova, Helen
    Powiązania:
    https://bibliotekanauki.pl/articles/281536.pdf
    Data publikacji:
    2020
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    applied mechanics
    biomechanics
    waves in fluids
    wave reflection
    medical diagnostics
    Opis:
    In the study, wave propagation along aorta is studied for different normal and pathological conditions in distal arteries. The mathematical model is based on the axisymmetric incompressible Navier-Stokes equations for blood and momentum equations for an incompressible viscoelastic arterial wall. The solution has been found as a superposition of forward and backward running waves. The blood pressure and flow curves measured by ultrasound in larger systemic arteries of ten healthy volunteers have been used for identification of the model parameters. It is shown that individual geometry plays an essential role in the location of positive and negative wave reflection sites along the aorta and, thus, in the pressure and flow patterns as well as blood distribution into the side branches. The model is validated by comparative study with the same dependencies computed previously on a 55-tube model as well as on the measurement data. The model can be used for determination of the individual parameters for patient-specific cardiovascular models and further in silico modeling of the outcomes of surgical and therapeutic procedures.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2020, 58, 1; 17-34
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Theoretical and Experimental Study on Detonation Wave Propagation in Cylindrical High Explosive Charges with a Wave-shaper
    Autorzy:
    Pan, J.
    Zhang, X.
    He, Y.
    Deng, Q.
    Guan, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/358040.pdf
    Data publikacji:
    2016
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    high explosive
    detonation wave
    Mach reflection
    wave-shaper
    Whitham method
    Opis:
    The use of a cylindrical high-explosive charge with a wave-shaper is an efficient way to obtain an ultra-high pressure and a convergent detonation wave. An analysis of flow fields corresponding to the regular and Mach reflection of detonation waves in a cylindrical high-explosive charge with a wave-shaper is presented in this paper. The pressure, flow velocity and triple point growth angle of the Mach stem were calculated. The Mach stem height was also determined by using the modified Whitham method. The results show that the Mach stem height rises from zero at the critical angle of Mach reflection and changes to the Chapman-Jouguet detonation state with the propagation of the detonation waves. Shock indentation experiments were conducted, in which a wave-shaper was used in a cylindrical high-explosive charge to form Mach reflection detonation waves. The results showed that the discrepancy between the experimental results and the theoretical calculations was less than 15%, which proves the validity of the proposed theoretical model.
    Źródło:
    Central European Journal of Energetic Materials; 2016, 13, 3; 658-676
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Waves in elastic materials and structures
    Autorzy:
    Wesołowski, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/332103.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Akustyczne
    Tematy:
    wave propagation
    discontinuity
    reflection and propagation speed
    Opis:
    The mathematical description of waves propagation in elastic materials and structures is presented. Particularly, the considerations concern the water as a transmission medium for acoustic waves. The following issues are discussed: discontinuity, reflection, and propagation speed, among others.
    Źródło:
    Hydroacoustics; 2015, 18; 167-179
    1642-1817
    Pojawia się w:
    Hydroacoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental study of hydraulic response of smooth submerged breakwaters to irregular waves
    Autorzy:
    Mahmoudof, S.M.
    Hajivalie, F.
    Powiązania:
    https://bibliotekanauki.pl/articles/2078821.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Instytut Oceanologii PAN
    Tematy:
    submerged breakwater
    irregular wave
    experimental study
    transmission
    reflection
    coastal area
    Opis:
    This paper presents the results of a laboratory experiment on transmission, reflection, and dissipation of irregular waves over smooth impermeable submerged breakwaters. Experiments included 75 JONSWAP-based irregular waves with five different wave characteristics generated at three water depths in a 2D wave flume. The investigated breakwater sections were three rectangular breakwaters with different widths, a toothed rectangular breakwater, and a trapezoidal breakwater with a slope of 1:2. A new comprehensive dimensionless parameter (β) was proposed representing both wave hydrodynamic and breakwater geometry characteristics. This parameter could be employed as a suitable descriptive option to make an accurate estimate of the hydraulic performances of submerged breakwaters. The β parameter is composed of four conventional simple dimensionless variables. However, the results revealed that the relative submergence depth significantly affects the hydraulic responses of submerged breakwaters. The transmission, reflection and dissipation of waves show a logarithmic growth, a logarithmic reduction, and a quadratic decreasing trend against the increasing of β parameter, respectively. The verifications of results revealed the high efficiency of β parameter for data reported by Carevic et al. (2013) with R2 = 0.88 and high agreement with predictions made by Van der Meer et al. (2005) formulation with R2 = 0.93.
    Źródło:
    Oceanologia; 2021, 63, 4; 448-462
    0078-3234
    Pojawia się w:
    Oceanologia
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Reflection and Transmission of Plane Wave at an Interface Between Two Rotating Micropolar Piezoelectric Solid Half-Spaces
    Autorzy:
    Singh, Baljeet
    Sangwan, Asha
    Singh, Jagdish
    Powiązania:
    https://bibliotekanauki.pl/articles/2141703.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    plane wave
    micropolar piezoelectricity
    reflection and transmission
    amplitude ratios
    energy ratios
    rotation
    Opis:
    In this paper, we investigate a problem on reflection and transmission of plane-waves at an interface between two dissimilar half-spaces of a transversely isotropic micropolar piezoelectric material. The entire model is assumed to rotate with a uniform angular velocity. The governing equations of rotating and transversely isotropic micropolar piezoelectric medium are specialized in a plane. Plane-wave solutions of two-dimensional coupled governing equations show the possible propagation of three coupled plane-waves. For an incident plane-wave at an interface between two dissimilar half-spaces, three reflected and three transmitted waves propagate with distinct speeds. The connections between the amplitude ratios of reflected and transmitted waves are obtained. The expressions for the energy ratios of reflected and transmitted waves are also obtained. A numerical example of the present model is considered to illustrate the effects of rotation on the speeds and energy ratios graphically.
    Źródło:
    Archives of Acoustics; 2021, 46, 4; 623-635
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Experimental investigation of cementitious materials using the prism technique
    Autorzy:
    Messaoudi, Rahma
    Bouzerira, Cherif
    Grimes, Morad
    Oucief, Hocine
    Powiązania:
    https://bibliotekanauki.pl/articles/396269.pdf
    Data publikacji:
    2020
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    prism technique
    cementitious material
    compressional wave
    shear wave
    reflection coefficient
    technika pryzmatyczna
    materiał cementowy
    ściskanie
    fala uderzeniowa
    współczynnik odbicia
    Opis:
    Numerous studies have shown that the non-destructive testing has proved the exceptional role in supervising the quality of concrete. Today, they represent an alternative that contributes to the resolution of materials diagnostic problems without altering them. This work presents an experimental study using a pulse-echo method that has the advantage of generating two types of wave (compressional and shear) by a mode conversion using just one transducer. The samples were made in a prismatic form. The results recovered from backscattered echoes are extracted using an estimation algorithm. These data were exploited to determine velocities of the tested material then the reflection coefficients for related them with the compressive strength. The tests were conducted with six samples with varied water/cement ratio. The results obtained showed that the prism technique has the potential to evaluate characteristics cementitious material using this proposed process.
    Źródło:
    Civil and Environmental Engineering Reports; 2020, 30, 1; 196-212
    2080-5187
    2450-8594
    Pojawia się w:
    Civil and Environmental Engineering Reports
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Reflection and transmission at the boundary surface of modified couple stress thermoelastic media
    Autorzy:
    Kumar, R.
    Kumar, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/264443.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    termoelastyczność
    fala podłużna
    fala poprzeczna
    wskaźniki amplitudy
    modified couple stress thermoelastic solid
    longitudinal wave
    transverse wave
    reflection
    transmission
    amplitude ratios
    Opis:
    In this paper the reflection and transmission at a plane interface in modified couple stress generalized thermoelastic solid half spaces in the context of Loard-Shulman (LS) and Green-Lindsay (GL) theories in welded contact are investigated. Amplitude ratios of various reflected and transmitted waves are obtained due to incidence of a set of coupled longitudinal waves and coupled transverse waves. It is found that the amplitude ratios of various reflected and transmitted waves are functions of the angle of incidence, frequency and are affected by the couple stress properties of the media. Some special cases are deduced from the present formulation.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2016, 21, 1; 61-81
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Conversion excitation of intense sound fields in crystals
    Autorzy:
    Alshits, V.
    Bessonova, D.
    Lyubimov, V.
    Radowicz, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/127714.pdf
    Data publikacji:
    2014
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    elastic wave
    resonance reflection
    conversion
    pump wave
    anisotropy
    diffraction divergence
    fala sprężysta
    odbicie rezonansu
    konwersja
    fala pompująca
    anizotropia
    rozbieżność dyfrakcji
    Opis:
    The resonant excitation of an intense elastic wave in a crystal is described through a special nonspecular reflection close to a conversion when almost all the energy from the incident pump wave falls into the near-surface narrow high-intensity reflected beam. The resonance arises when the excited reflected wave is close to the bulk eigenmode satisfying the condition of free boundary. It is shown that the choice of the crystal surface parallel to a symmetry plane allows simultaneous optimization of reflection geometry when the intensity maximum for the excited wave is accompanied by the intensity minimum for the other (parasite) reflected wave. And the conversion criterion of vanishing of the above minimum is determined by one definite condition on elastic moduli. On this basis the series of real monoclinic, orthorhombic and hexagonal crystals were chosen where the resonant reflection in non-symmetric sagittal planes proves to be very close to conversion.
    Źródło:
    Vibrations in Physical Systems; 2014, 26; 13-20
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Reflection and transmission in non-local couple stress micropolar thermoelastic media
    Autorzy:
    Gupta, Deepa
    Malik, Sangeeta
    Kumar, Krishan
    Sharma, Raj Kumar
    Powiązania:
    https://bibliotekanauki.pl/articles/2174196.pdf
    Data publikacji:
    2022
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    termosprężystość
    liczba falowa
    para
    non-local
    thermoelastic solid
    amplitude ratios
    reflection
    transmission
    couple stress
    wave number
    Opis:
    We have studied the problem of homogenous, isotropic non-local couple stress micropolar thermoelastic solid in the absence of body forces, couple density and heat resources. The reflection and transmission of waves at the interface of two distinct media have been investigated. It is observed that amplitude ratios of various reflected and transmitted waves are functions of wave number of incident waves and are affected by the non-local parameter of thermoelastic solid.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2022, 27, 2; 53--76
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Scattering of interface wave by bottom undulations in the presence of thin submerged vertical wall with a gap
    Autorzy:
    Dolai, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/265016.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    dyfrakcja fal
    fala powierzchniowa
    fala grawitacyjna
    submerged vertical wall
    perturbation analysis
    interface wave scattering
    sinusoidal bottom
    Galerkin approximations
    zero-order reflection coefficient
    first-order reflection coefficient
    Opis:
    In this paper, the problem of interface wave scattering by bottom undulations in the presence of a thin submerged vertical wall with a gap is investigated. The thin vertical wall with a gap is submerged in a lower fluid of finite depth with bottom undulations and the upper fluid is of infinite height separated by a common interface. In the method of solution, we use a simplified perturbation analysis and suitable applications of Green’s integral theorem in the two fluid regions produce first-order reflection and transmission coefficients in terms of integrals involving the shape function describing the bottom undulations and solution of the scattering problem involving a submerged vertical wall present in the lower fluid of uniform finite depth. For sinusoidal bottom undulations, the first-order transmission coefficient vanishes identically. The corresponding first-order reflection coefficient is computed numerically by solving the zero-order reflection coefficient and a suitable application of multi-term Galerkin approximations. The numerical results of the zero-order and first-order reflection coefficients are depicted graphically against the wave number in a number of figures. An oscillatory nature is observed of first-order reflection coefficient due to multiple interactions of the incident wave with bottom undulations, the edges of the submerged wall and the interface. The first-order reflection coefficient has a peak value for some particular value of the ratio of the incident wavelength and the bottom wavelength. The presence of the upper fluid has some significant effect on the reflection coefficients.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2016, 21, 2; 303-322
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Charakterystyka technologii georadarowej i możliwe kierunki jej doskonalenia
    Characteristic of geo-radar technology and possible directions for its improviement
    Autorzy:
    Wutke, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/143892.pdf
    Data publikacji:
    2018
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Komunikacji Rzeczpospolitej Polskiej
    Tematy:
    georadar
    GPR
    stała dielektryczna
    współczynnik odbicia
    długość fali
    Ground Penetrating Radar
    dielectric constant
    reflection coefficient
    wave length
    Opis:
    Technologia georadarowa (GPR) jest powszechnie stosowana do obrazowania obszarów podpowierzchniowych m.in. nawierzchni drogowych. Jest to metoda nieniszcząca, wykorzystująca do wykrywania sygnałów odbitych od konstrukcji podpowierzchniowych promieniowanie elektromagnetyczne w paśmie mikrofalowym. GPR transmituje do ziemi fale elektromagnetyczne, a gdy te uderzą w zakopany obiekt lub granicę materiałów o różnych stałych dielektrycznych, antena odbiorcza rejestruje zmiany w sygnale zwrotnym. Ważne jest, aby mieć podstawową wiedzę na temat działania georadaru, ponieważ jego możliwości, ale i ograniczenia są bezpośrednio skorelowane z nauką. W artykule charakteryzowano technologię georadarową ze zwróceniem szczególnej uwagi na ograniczenia stosowania metodologii. Opisuje możliwości zwiększenia efektywności pomiarów georadarowych i nowe obszary zastosowań.
    Ground Penetrating Radar (GPR) technology is widely used for imaging the subsurface areas, including road structures. It is a non-destructive method that uses electromagnetic waves to detect signals reflected from sub-surface constructions. GPR transmits electromagnetic waves to the ground, and when these hit a buried object or boundary of materials with different dielectric parameters, the receiving antenna registers changes in the reflected signal. It is important to have a basic knowledge related to the operation of GPR, because its capabilities, but also limitations are directly correlated with science. The article describes GPR technology with particular attention to the limitations of the methodology. It describes the possibilities of increasing the GPR efficiency and new areas of applications.
    Źródło:
    Drogownictwo; 2018, 9; 276-280
    0012-6357
    Pojawia się w:
    Drogownictwo
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Water wave scattering by an infinite step in the presence of an ice-cover
    Autorzy:
    Ray, S.
    De, S.
    Mandal, B. N.
    Powiązania:
    https://bibliotekanauki.pl/articles/265982.pdf
    Data publikacji:
    2019
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    fala wodna
    pokrywa lodowa
    aproksymacja Galerkina
    water wave scattering
    ice cover
    infinite step
    integral equation
    Galerkin approximation
    reflection and transmission coefficients
    Opis:
    The classical problem of water wave scattering by an infinite step in deep water with a free surface is extended here with an ice-cover modelled as a thin uniform elastic plate. The step exists between regions of finie and infinite depths and waves are incident either from the infinite or from the finite depth water region. Each problem is reduced to an integral equation involving the horizontal component of velocity across the cut above the step. The integral equation is solved numerically using the Galerkin approximation in terms of simple polynomial multiplied by an appropriate weight function whose form is dictated by the behaviour of the fluid velocity near the edge of the step. The reflection and transmission coefficients are obtained approximately and their numerical estimates are seen to satisfy the energy identity. These are also depicted graphically against thenon-dimensional frequency parameter for various ice-cover parameters in a number of figures. In the absencje of ice-cover, the results for the free surface are recovered.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2019, 24, 4; 157-168
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-13 z 13

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