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1

Scattering of electromagnetic waves by plasma layer sandwiched between two layers of thin glass

Lavrushev Vladimir Niriforovich, Dautov Osman Shakirovich, Al-Abadi Mohammad Sadon, Almakki Ali Nadhim Jbarah

Przegląd Elektrotechniczny

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2023

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R. 99, nr 4

102--106

EN

A technique for monitoring plasma parameters for antenna measurements using a model of low-pressure fluorescent lamps is studied. The physical parameters of the plasma in the layout were obtained using microwave interferometry measurements. Using an accurate analytical model, it is shown that, this layer absorbs almost half the incident power. The noticeable dissipation of electromagnetic waves in the frequency band makes it possible to consider a thin layer of plasma as a plasma absorber.

PL

Badana jest technika monitorowania parametrów plazmy do pomiarów antenowych przy użyciu modelu niskociśnieniowych lamp fluorescencyjnych. Parametry fizyczne plazmy w układzie uzyskano za pomocą pomiarów interferometrii mikrofalowej. Korzystając z dokładnego modelu analitycznego, wykazano,że warstwa ta pochłania prawie połowę mocy padającej. Zauważalne rozpraszanie fal elektromagnetycznych w paśmie częstotliwości pozwala uznać cienką warstwę plazmy za absorber plazmy.

2

Tunneling throught a barrier under transverse magnetic field and I-V characteristic

Papadopoulos George J.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2018

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Vol. 22. No 2

125--133

EN

The case whereby the transmission coefficient through a barrier, sandwiched by semiconductor reservoirs, under bias is provided by a general formula involving the logarith micwave function derivative at the barrier entrance is now extended to include the influence of magnetic field perpendicular to the longitudinal barrier direction. Under the circumstances, theequation governing the logarithmic wave function derivative is appropriately modified via aneffective potential energy which takes account of the magnetic field. Subsequently, the procedurefor obtaining the transmission coefficient is applied to the case involving a smooth double, as wellas quadruple, barrier for which theI-V characteristic is obtained. The results show reduction incurrent with increase in the magnetic field, up to a certain value of bias. Furthermore, increasein temperature exhibits increase in current as well as movement of the current peaks in the I-V curves towards lower bias.

3

Parametric comparison of rectangular and circular pontoons performance as floating breakwater numerically

Tabatabaei S. M. R., Zeraatgar H.

Polish Maritime Research

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2018

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S 1

94--103

EN

Rectangular and circular pontoons are one of the most widely cross-sections used as floating breakwaters (FB). Although, there are several articles on comparison of behavior of rectangular and circular floating breakwaters however, the Authors try to show some details of difference between these two types where they have not been addressed before. To do so, transmission coefficient (Ct), as a measure of merit, of similar rectangular and circular sections is numerically compared. A computer code is developed for two-dimensional hydrodynamic analysis of floating breakwater based on diffraction theory in frequency domain in regular waves with any configuration of mooring line. The numerical method is the finite element method and validated by comparing with experimental and numerical results. Three types of rectangular sections are defined equivalent to circular section and a numerical comparison is made between 100 similar sections. The Ct versus wave frequency has been considered in detail and three new points called LMinF, LMaxF and LMaxCt are introduced. It has been shown that LMinF and LMaxF of circular section are greater and LMaxCt is much smaller than equivalent rectangular section. The LMaxCt of both sections are very dependent to new nondimensional parameter B/D (Breadth/Draft). Although, rectangular sections are more common for floating breakwater, however the results of this study show that possibility of using circular sections must be also considered.

4

Analytical study of the reflection and transmission coefficient of the submarine interface

Zhang G., Hao C., Yao C.

Acta Geophysica

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2018

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Vol. 66, no. 4

449--460

EN

The analytical study of the reflection and transmission coefficient of the seafloor interface is essential for the characterization of the ocean bottom in marine seismic exploration. Based on the boundary conditions of the seafloor interface, the analytical expression of the reflection and transmission coefficient at the submarine interface is derived in this study by using the steady-state wave solution of the elastic wave in a homogeneous, isotropic medium. With this analytical expression, the characteristics of the reflection and transmission coefficient at the submarine interface are analysed and discussed using critical angles. The results show that the change in the reflection and transmission coefficient with the incidence angle presents a ‘‘segmented’’ characteristic, in which the critical angle is the dividing point. The amplitude value and phase angle of the coefficient at the submarine interface change dramatically at the critical angle, which is related to the P- and S-wave velocities in the seabed layer. Compared with the stiff seabed, the soft seabed has a larger P-wave critical angle and an absence of the converted S-wave critical angle, owing to the low P- and S-wave velocities in the solid seabed layer. By analysing and discussing the special changes that occur in the coefficient values at the critical angle, the reflection and transmission characteristics of the different incident angles are obtained. Synthetic models of both stiff and soft seafloors are provided in this study to verify the analytical results. Finally, we compared our synthetic results with real data from the Gulf of Mexico, which enabled the validation of our conclusions.

5

The dependence of the chemical composition of Al-Ti-Cr multi-component coatings on parameters of the arc-evaporation process

Kacprzyńska-Gołacka J., Słomka Z., Osuch-Słomka E., Rydzewski M., Mazurkiewicz A., Smolik J.

Journal of Machine Construction and Maintenance - Problemy Eksploatacji

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2017

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no. 3

53--57

EN

One of the most perspective directions of the development of surface engineering concerns hard multicomponent coatings prepared using PVD technologies. Reactive arc vacuum sputtering is the best known and most widely used technology for manufacturing multicomponent antiwear coatings. Using this method requires the application of suitably composed targets to obtain coatings with suitable compositions. One of the problems that occur during the design of multicomponent coatings is the selection of the chemical composition of the cathode of the arc source. In the case of the arc vacuum method, the chemical composition of the cathode does not coincide with the chemical composition of the obtained coating. It is connected with the „transfer coefficient.” It depends mainly on the intensity of the evaporation of the material from multicomponent targets, and it changes depending on the melting temperature of the element. The authors present the results of the analysis of the transmission rate of the chemical composition of cathodes composed based on elements with different melting points (Al, Ti, Cr). The article presents the influence of chemical composition of twoand three-component cathodes on the chemical composition of the obtained coating. The study was carried out with the EDS method using a scanning electron microscope with a chemical composition analyser.

PL

Jednym z najbardziej perspektywicznych kierunków rozwoju inżynierii powierzchni są powłoki wieloskładnikowe wytwarzane przy wykorzystaniu technologii plazmowych. Jedną z powszechnie stosowanych technik wytwarzania przeciwzużyciowych powłok wieloskładnikowych jest reaktywne odparowanie łukiem elektrycznym. Technika ta umożliwia wykorzystywanie targetów wieloskładnikowych, które pozwalają na otrzymywanie powłok o zróżnicowanym składzie chemicznym. Jednym z problemów występujących na etapie projektowania powłok wieloskładnikowych jest dobór składu chemicznego katody źródła łukowego. W przypadku metody łukowo-próżniowej skład chemiczny katod nie pokrywa się ze składem chemicznym otrzymanej powłoki. Związane jest to z intensywnością przenoszenia składu chemicznego katody. Zależy on głównie od intensywności parowania danego materiału z targetów wieloskładnikowych i zmienia się w zależności od wielu różnych czynników związanych zarówno z procesem technologicznym, konfiguracją technologiczną, jak również z parametrami katody oraz procesem jej wytwarzania. W pracy autorzy przedstawili wyniki analizy głównych czynników mających istotny wpływ na intensywność przenoszenia składu chemicznego z katody na skład chemiczny powłoki. Autorzy skupili się w pracy głównie na analizie czynników związanych z parametrami katody źródła łukowego. Zbadano intensywność przenoszenia się składu chemicznego katod dwu- oraz trzyskładnikowych na bazie aluminium tytanu oraz chromu na skład chemiczny otrzymanej powłoki wieloskładnikowej. Badanie zrealizowano metodą EDS przy wykorzystaniu mikroskopu elektronowego wyposażonego w analizator składu chemicznego.

6

Simulation of neutron irradiation influence on p-n-p bipolar transistor characteristics

Miskiewicz S., Komarov F., Komarov A., Żukowski P., Michailov V.

Przegląd Elektrotechniczny

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2016

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R. 92, nr 11

236--238

EN

We have developed numerical model and software to simulate the ionizing radiation influence on the bipolar transistor parameters. The software allows to calculate the input and output characteristics, the current transmission coefficient and other parameters under the irradiation for various temperatures, base and collector voltages.

PL

Opracowaliśmy model numeryczny i oprogramowanie do symulacji wpływu promieniowania jonizującego na parametry tranzystorów bipolarnych. Oprogramowanie pozwala obliczyć parametry wejściowe i wyjściowe, aktualny współczynnik transmisji i inne parametry na podstawie napromieniowania dla różnych temperatur, napięć bazy i kolektora.

7

Real time quantum tunneling

Papadopoulos G. J.

TASK Quarterly : scientific bulletin of Academic Computer Centre in Gdansk

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2015

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Vol. 19, No 1

65--74

EN

The time evolution of the probability and current densities stemming from an initial tate of a particle in the form of a wave packet on the left hand side of a square barrier is studied. In particular, the space distribution at a given time of the above densities is given. Furthermore, the evolution in time at the entrance and exit of the barrier is given. The numerical results show repeated reversal in the current density at the barrier entrance, while being unidirectional at the exit. However, the probability entering the barrier over a long time equals the corresponding probability exiting the barrier. Owing to the fact that the wave packet expands on both of its sides, as time goes by, it is possible to have transmission even if the particle’s initial momentum points away from the barrier. The effect, in question, becomes evident in a diagram for the transmission coefficient in terms of the particle initial momentum, over a relatively small region.

8

New Textiles Designed for Anti-Radar Camouflage

Redlich G., Obersztyn E., Olejnik M, Fortuniak K, Bartczak A, Szugajew L, Jarzemski J.

Fibres & Textiles in Eastern Europe

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2014

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Vol. 22, no. 1 (103)

34--42

EN

This paper presents newly designed textiles (woven and knitted fabrics) for camouflage against radar, with a particular emphasis on the conductive yarns applied and their distribution throughout the structure of the goods. The levels obtained for the coefficients of re- flection and the transmission of electromagnetic waves have been discussed for woven and knitted fabrics, both raw and those subjected to finishing treatment. These parameters were determined using two methods: waveguide applicators and in the space in a semi-anechoic chamber within the time domain. The issues this publication covers are an integral part of research on developing textile products featuring a broad spectrum of masking, i.e. within the visible (VIS), near infrared (IR), and that of the subject - the anti-radar band. The first two types of camouflage were discussed in an earlier publication entitled “Assessment and Verification of the Functionality of New, Multi-component, Camouflage Materials” (Fibres & Textiles in Eastern Europe 2013; 21, 5(101): 73-79).

PL

W artykule przedstawiono nowoopracowane konstrukcje włókiennicze (tkaniny, dzianiny) maskujące przeciwradiolokacyjnie, ze szczególnym uwzględnieniem zastosowanych przędz konduktywnych oraz ich rozkładu w strukturze wyrobów. Omówiono poziomy uzyskanych wartości współczynników odbicia i transmisji fal elektromagnetycznych, zarówno dla tkanin i dzianin surowych, jak i poddanych obróbce wykańczalniczej. Parametry te były wyznaczane z zastosowaniem dwóch metod tj. z wykorzystaniem aplikatorów falowodowych oraz w przestrzeni w komorze bezechowej w domenie czasu. Zagadnienia ujęte w niniejszej publikacji stanowią integralną część badań nad opracowaniem wyrobów włókienniczych o szerokim spektrum maskowania, tj. w zakresie widzialnym (VIS), bliskiej podczerwieni (IR) oraz przedmiotowym czyli przeciwradiolokacyjnym. Dwa pierwsze rodzaje maskowania zostały przedstawione we wcześniejszej publikacji pt. „Assessment and verification of functionality of new, multi-component, masking materials ”(Fibres & Textiles in Eastern Europe 2013; 21, 5(101): 73-79).

9

A general formula for the transmission coefficient through a barrier and application to I-V characteristic

Papadopoulos G. J.

Materials Science Poland

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2011

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Vol. 29, No. 4

266--271

EN

A general formula providing the transmission coefficient through a given barrier, sandwiched by semiconductor reservoirs under bias is presented in terms of the incoming carrier energy and the logarithmic wave function derivative at the start of the barrier. Furthermore, the formula involves the carrier effective masses in the barrier and reservoir regions. The procedure employed is based on solving an appropriate Riccati equation governing the logarithmic derivative along the barrier width at the end of which it is known in terms of the carrier energy and applied bias. On account of the facility provided for obtaining the transmission coefficient we obtained the I-V characteristic of a quantum dot carved barrier, which exhibits a region of quite a large negative differential resistance together with a high peak to valley ratio. Under the circumstances, the possibility of developing a nanostructure switch utilizing a small variation in the applied bias exists.

10

Conductivity and transmission coefficients of ultra-thin disordered metallic films

Spisak B.J., Paja A.

Materials Science Poland

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2006

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Vol. 24, No. 3

605--609

EN

The diffusive motion of quasi-two-dimensional electron gas through an ultra-thin system of disordered potentials is considered. In such system the Fermi sphere splits into a set of independent sheets due to the small thickness of the system. Each sheet can be seen as an electron sub-band. The electron transport goes through these sub-bands independently. The sum of electrical conductivities over these sub-bands determines the total current which is calculated for ultra-thin films of cesium. We also present the relation between our approach and Landauer formalism based on the notation of the transmission coefficient.