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1

Series Expanding of the Ultrasound Transmission Coefficient Through a Multilayered Structure

Chitnalah Ahmed, Aouzale Noureddine, Jakjoud. Hicham

Archives of Acoustics

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2023

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Vol. 48, No. 1

71--79

EN

To calculate the transmission coefficient of ultrasonic waves through a multi-layered medium, a new approach is proposed by expanding it into Debye’s series. Using this formalism, the transmission coefficient can be put in the form of resonance terms series. From this point of view, the relative amplitude of the transmitted wave can be considered as an infinite summation of terms taking into account all possible reflections and refractions on each interface. Our model is then used to investigate interaction between the ultrasonic plane wave and the N-plane-layer structure. Obviously, the resulting infinite summation has to be reduced to a finite one, according to some level of accuracy. The numerical estimation of the transmission coefficient using the exact expression (Eq. (1)) is then compared to the one of our method in the case of two or three plane-layer structure. The effect of the order of the finite summation on the calculated value of the transmission coefficient is, as well, studied. Finally, our proposed method may be used, with the decomposition into Gaussian beams of a pressure field created by a circular source, to draw a 3D image of the pressure field transmitted through a multilayered structure.

2

The game in decrypting geometry which hides the history of place

Magdziak-Grabowska M.

Czasopismo Techniczne. Architektura

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2015

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Y. 112, iss. 9-A

179--184

EN

The city is a multilayered structure composed from multiple pieces, each of which has been subjected to the individual influence of history and changes of time. The city is a game board where architects play at refilling empty fragments. The rules of the game allow geometric deformations of space, in order to establish the context of the concealed history of the place. The goal of the game is to bring what is most valuable and precious from the existing urban structure, or build a new value that will last the test of time.

PL

Miasto to wielowarstwowa struktura, złożona z wielu fragmentów, z których każdy ulegał indywidualnym wpływom historii i przemianom w czasie. Miasto to plansza do gry, na której architekci bawią się w uzupełnianie pustych fragmentów. Reguły gry pozwalają na geometryczne deformacje przestrzeni, w celu nawiązania kontekstu do skrywanej historii miejsca. A celem gry jest wydobycie z istniejącej tkanki urbanistycznej tego, co wartościowe i cenne, lub zbudowanie nowej wartości, która przetrwa próbę czasu.

3

Multilayered structure of the Dzukija and Dainava tills and their correlation in South Lithuania

Baltrńnas V., Karmaza B., Pukelyte V.

Geological Quarterly

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2008

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Vol. 52, No 1

91-91

EN

Lithuanian Pleistocene tills have a multilayered strucure, as established using borehole log data and various analytical methods. Locally it can be observed visually. The structure of the oldest Middle Pleistocene Dzńkija (Elster 1) and Dainava (Elster 2) tills was in vestigated in their areal stratotype in South Lithuania. Logs of three boreholes were chosen for detailed analysis. Their triangular distribution enables evaluation of the variation of till material in N to S and NW to SE di rec tions. Grain-size analysis was performed for tills from all three boreholes and the index of relative entropy of grain-size was calculated. The composition of the Dzńkija and Dainava tills succession indicators advances referable to at least two glaciations and their stages. The Dzńkija tills were formed by glaciers ad vancing from the north across Devonian strata. The Dainava till were left by glaciers advancing from NW across Lower Palaeozoic and Mesozoic rocks. The macroscopically homogeneous upperlayers of the Dzńkija till and the upper and lower layers of the Dainava till have a rhythmic multi layered structure revealed by log and grain-size data. The sedimentological na ture of this rhythmicity is partly shown by variation analysis of the relative entropy of grain-size composition in vertical succession. The index of relative entropy, reflect ing the de gree of mixing, allowed the destination of four zones of entropy (better mixing) in the vertical succession. These zones some times correlate well between widely separated sections. Their presence may be explained by a repeated in put of till material into the basal part of the glacier during its activation (stage, phase).

4

Przegląd podstawowych hipotez "linii łamanej" płyt i powłok kompozytowych

Wilde R., Zborała P.

Zeszyty Naukowe Politechniki Poznańskiej. Budowa Maszyn i Zarządzanie Produkcją

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2007

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Nr 7

165-175

PL

Praca stanowi przegląd podstawowych hipotez „linii łamanej", które znalazły zastosowanie w teoretycznej analizie płyt i powłok kompozytowych. Spośród wielu znanych w literaturze teorii w artykule omówiono jedynie te o charakterze pierwotnym. Zaprezentowano trzy główne hipotezy: Lekhnitskiego, Ambartsumiana oraz Reissnera. Dokonano krótkiej charakterystyki i wstępnie porównanano wymieni oni one teorie. Omówione zostafy związane z hipotezami linii łamanej warunki ciągłości funkcji odkształceń (Zig-Zag) i naprężeń ścinających (interlaminar continuity).

EN

The purpose of this paper is to present basic knowlegde about fundamental "broken-line" hypothesis that deal with multilaycred composite structures. Three main theories were described: Lekhnitskii's, Ambartsumian's and Reissner's. Only Murakami's contribution to Reissner's theory was presented. Comparing the theories was of strictly theoretical meaning and none of the numerical calculations were performed. The proper numerical computation will be provided in further works.

5

New type of microstrip antenna with ferroelectric layer

Modelski J., Yashchyshyn Y.

Journal of Telecommunications and Information Technology

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2001

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nr 4

37-40

EN

A new type of microstrip antenna is proposed using a voltage-controlled ferroelectric thin tape in the multilayered structure. This paper presents the ferroelectric thin tape, its theoretical analysis and design. The results indicate that this concept has many advantages, is very practical and promising. It gives possibilities of several applications, e.g. in smart antennas.