Wyniki wyszukiwania - Biblioteka Nauki

1

Investigation of 2D-photonic crystal resonant cavity based WDM demultiplexer

100%

Kannaiyan V. , Savarimuthu R. , Dhamodharan S. K.

Opto-Electronics Review

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2018

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tom Vol. 26, No. 2

108--115

EN

In this attempt, Two Dimensional Photonic Crystal (2DPC) Quasi Square Ring Resonator (QSRR) based four channel demultiplexer is proposed and designed for Wavelength Division Multiplexing systems. The performance parameters of the demultiplexer such as transmission efﬁciency, passband width, line spacing, Q factor and crosstalk are investigated. The proposed demultiplexer is composed of bus waveguide, drop waveguide and QSRR. In the proposed demultiplexer, the output ports are arranged separately in odd and even number, where an odd number of ports are located on the right side and even number of ports are located on the left side of the bus waveguide that are used to reduce the channel interference or crosstalk. Further, the refractive index of rods around the center rod is increased linearly one to another in order to improve the signal quality. The resonant wavelengths of the proposed demultiplexer are of 1521.1 nm, 1522.0 nm, 1523.2 nm and 1524.3 nm, respectively. The footprint of the device is of 180.96 µm². Then, a four channel point to point network is designed and the proposed four channel demultiplexer is implemented by replacing a conventional demultiplexer. Finally, functional parameters of the network, namely, BER, receiver sensitivity and Q factor are estimated by varying the link distance. This attempt could create new dimensions of research in the domain of photonic networks.

2

Quo vadis, ultrasonics of bone? Present state and future trends

100%

Laugier P. , Talmant M. , Pham T.-L.

Archives of Acoustics

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2008

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tom Vol. 33, No. 4

553-564

EN

Although it has been over 20 years since the first recorded use of a quantitative ultrasound (QUS) technology to predict bone fragility, the field has not yet reached its maturity. QUS have the potential to predict fracture risk in a number of clinical circumstances and has the advantages of being non-ionizing, inexpensive, portable, highly acceptable to patients and repeatable. However, the wide dissemination of QUS in clinical practice is still limited and suffering form the absence of clinical consensus on how to integrate QUS technologies in bone densitometry armamentarium. There are a number of critical issues that need to be addressed in order to develop the role of QUS within rheumatology. These include issues of technologies adapted to measure the central skeleton, data acquisition and signal processing procedures to reveal bone properties beyond bone mineral quantity and elucidation of the complex interaction between ultrasound and bone structure. In this presentation, we review recent developments to assess bone mechanical properties. We conclude with suggestions of future lines and trends in technology challenges and research areas such as new acquisition modes, advanced signal processing techniques, and models.

3

Performance analysis of an eight channel demultiplexer using a 2D-photonic crystal quasi square ring resonator

100%

Kannaiyan V. , Savarimuthu R. , Dhamodharan S. K.

Opto-Electronics Review

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2017

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tom Vol. 25, No. 2

74--79

EN

Recent years, the design of photonic crystal (PC) based optical devices is receiving keen interest in research and scientific community. In this paper, two dimensional (2D) PC based eight channel demultiplexer is proposed and designed and the functional characteristics of demultiplexer namely resonant wavelength, transmission efficiency, quality factor, spectral width, channel spacing and crosstalk are investigated. The demultiplexer is designed to drop the wavelength centred at 1537.6 nm, 1538.5 nm, 1539.4 nm, 1540.4 nm, 1541.2 nm, 1541.9 nm, 1542.6 nm and 1543.1 nm. The proposed demultiplexer is primarily composed of bus waveguide, drop waveguide and quasi square ring resonator. The quasi square ring resonator and square ring micro cavity (inner rods) are playing a vital role for a desired channel selection. The operating range of the devices is identified through a photonic band gap (PBG) which is obtained using a plane wave expansion (PWE) method. The functional characteristics of the proposed demultiplexer are attained using a 2D finite difference time domain (FDTD) method. The proposed device offers low crosstalk and high transmission efficiency with ultra-compact size, hence, it is highly desirable for DWDM applications.

4

Basic Logic Gates in Two Dimensional Photonic Crystals for All Optical Device Design

100%

Sonth M. V. , Srikanth G. , Agrawal P. , Premalatha B.

International Journal of Electronics and Telecommunications

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2021

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tom Vol. 67, No. 2

247--261

EN

The research carried out in the field of optics and photonics with an idea to design and develop the all optical logic devices in the fascinating material known as photonic crystals (PhCs). The structural investigation reveals that the two dimensional (2-D) PhCs is more suitable for fabrication of optoelectronic components. In this article we have designed basic logic gates in 2-D PhCs as they are the building blocks for the construction of optical devices and in these, refractive index is periodically modulated with the wavelength. The understanding of light behaviour in complex PhCs helps in creating photonic band gap (PBG) that can prevent light of certain wavelength propagating in crystal lattice structure. For the selected geometry structure, three PBG bands will exists out of which two of them are transverse electric (TE) and one is transverse magnetic (TM) mode. The PBG bands in the TE mode ranges from 0.31( α λ ) to 0.46( α λ ), 0.61( α λ ) to 0.63( α λ ) and TM mode ranges from 0.86( α λ ) to 0.93( α λ ). The free space wavelength of 1550 nm is set for the finite difference time domain (FDTD) simulation of the structure. The response time and computational overhead required for the proposed OR gate is 0.128ps and 4.4MB is obtained. Also we calculated the extinction ratio for AND gate and NOT gate as 6.19 dB and 10.21 dB respectively.

5

Optical simulations and optimization of highly sensitive biosensor for cancer cell detection

86%

El Mouncharih A. , Takassa R. , Farkad O. , Tchenka A. , Ibnouelghazi E. A. , Abouelaoualim D.

Optica Applicata

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2023

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tom Vol. 53, nr 3

407--418

EN

In this work, using the two-dimensional finite difference time domain method, we are theoretically studying the optical properties of a two-dimensional photonic crystal biosensor based on silicon rods arranged as a square structure in an air bottom with two waveguides and a nanocavity. For this purpose, six different cells are infiltrated into the point defect. These six cells are Jurkat, HeLa, PC-12, MDA-MB-231, MCF-7, and basal cells. As a result, we have successfully detected cancer and benign cases of these cells through resonance peaks in the transmission spectrum. We evaluated the sensitivity, quality factor, detection limit, and figure of merit at different values for sensing region radius for optimization purposes. We report that we observed the maximum sensitivity of 1350 nm/RIU at 0.15 μm for the basal cell. Finally, the proposed biosensor can be a miniaturized structure with extreme sensitivity in cancer cell detection models.

6

Modeling the transient response of lightning current on grounding systems wind turbines

72%

Djaborebbi A. , Zegnini B. , Mahi D.

Przegląd Elektrotechniczny

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2021

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tom R. 97, nr 2

159--164

EN

The paper deals with transient analysis of grounding systems wind turbines.To improve the accuracy of lightning impact studies on wind power grid generation, it is necessary to develop faster, more accurate simulation tools and to use increasingly sophisticated models .First, we identify and characterize the different parameters that influence the behaviour of grounding systems, particularly when they broadcast a lightning current. To do this, an electromagnetic model from the theory of antennas equation’s by – Euler method with incorporating soil ionization allows to represent the behavior of an earthing system inthe frequency domain.. Different configurations with several complexity degrees have been simulated. To validate the obtained results, we compare our TLM results to the measurement results and FDTD simulation..A comparison between two different configurations of wind turbine grounding systems with comparing the transient potential, impulse impedance, and DC component of transient impedance between the two configurations when buried in soil. A number of illustrative computational examples are presented in the paper

PL

W celu poprawy dokładności badań wpływu wyładowań atmosferycznych na produkcję energii wiatrowej konieczne jest opracowanie szybszych i dokładniejszych narzędzi symulacyjnych oraz wykorzystanie coraz bardziej wyrafinowanych modeli. W pierwszej kolejności identyfikujemy i opisujemy różne parametry wpływające na zachowanie się systemów uziemienia, zwłaszcza gdy przekazują one prąd piorunowy. W tym celu opracowany został model elektromagnetyczny z teorii równań Eulera z wykorzystaniem jonizacji gruntu, który pozwala na przedstawienie zachowania się systemu uziemienia w dziedzinie częstotliwości. Symulowane są różne konfiguracje o kilku stopniach złożoności. W celu walidacji uzyskanych wyników, porównujemy nasze wyniki TLM z wynikami pomiarów i symulacji FDTD.Porównanie dwóch różnych konfiguracji uziemienia turbiny wiatrowej z porównaniem potencjału przemijającego, impedancji impulsowej i składowej stałej impedancji przemijającej pomiędzy tymi dwiema konfiguracjami, gdy są one zakopane w gruncie.

7

Automatyczna identyfikacja parametrów uproszczonego modelu ciała człowieka za pomocą algorytmu ewolucyjnego

72%

Januszkiewicz Ł. , Di-Barba P. , Hausman S.

Przegląd Telekomunikacyjny + Wiadomości Telekomunikacyjne

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2016

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tom nr 6

552--555, CD

PL

W artykule przedstawiono wykorzystanie algorytmu ewolucyjnego (Estra) do identyfikacji parametrów uproszczonego modelu ludzkiego ciała (fantomu). Uproszczony model ciała może być wykorzystywany do symulacji odstrojenia impedancyjnego anteny znajdującej się w pobliżu ciała. W artykule przedstawiono sposób określenia parametrów uproszczonego modelu za pomocą automatycznej procedury opartej na algorytmie ewolucyjnym i metodzie różnic skończonych w dziedzinie czasu (FDTD). Po określeniu wartości parametrów, uproszczony model został porównany do heterogenicznego modelu ludzkiego ciała. Modele porównano w oparciu o analizę dopasowania impedancyjnego anteny dipolowej znajdującej się na obu modelach.

EN

The paper presents the exploitation of a lowestorder algorithm of evolutionary computing (EStra) for identifying the parameters of a simplified human body model (phantom). A simplified model is well suited in view of the computationally-expensive field simulation of wearable antennas located in a close proximity to the human body. In the paper, an automated procedure based on evolutionary computing and Finite Difference Time Domain (FDTD) computational electrodynamics method is proposed to identify the parameters of the simplified model. Subsequently, after identifying the parameter values, the simplified model is compared to a heterogeneous anthropomorphic human-body model. The comparison is based on the analysis of impedance matching of the same dipole antenna located on both the anthropomorphic and simplified phantoms.

8

Diagnostics of breast cancer-complementary methods

72%

Michałowska-Samonek J. , Wac-Włodarczyk A.

Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska

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2011

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tom nr 3

28-31

EN

The study aims at comparing and presenting alternatives methods of breast cancer detection when compare with the mammography. A brief description and the physical basis underlying microwave tomography, optical tomography, galactography, termography and mammoscintigraphy have been done.

PL

Artykuł ma na celu zaprezentowanie wybranych metod alternatywnych do mammografii. Przedstawiono krótki opis podstaw fizycznych tomografii mikrofalowej, tomografii optycznej, galaktografii, termografii i mammoscyntygrafi.

9

Influence of spatial distribution and the type of material on the occurrence of bandgaps in phononic crystals

72%

Garus S. , Sochacki W. , Kwiatoń P. , Nabiałek M. , Petrů J. , Kubanek M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2023

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tom Vol. 71, nr 3

art. no. e144609

EN

The study investigated the effect of the fill factor, lattice constant, and the shape and type of meta-atom material on the reduction of mechanical wave transmission in quasi-two-dimensional phononic structures. A finite difference algorithm in the time domain was used for the analysis, and the obtained time series were converted into the frequency domain using the discrete Fourier transform. The use of materials with large differences in acoustic impedance allowed to determine the influence of the meta-atom material on the propagation of the mechanical wave.

10

Research on application of ground penetrating radar array method based on plane beam signal in diferent geological models

58%

Cui F. , Chen Y. , Zhang Y. , Du Y.

Acta Geophysica

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2021

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tom Vol. 69, no. 6

2241--2260

EN

The traditional common-offset ground penetrating radar method measures point by point along the survey line with a single transmitter and a single receiver. Due to the influence of the antenna radiation power and the low-pass filtering function of the earth medium, an intense amplitude gain cannot be obtained when the signal is intercepted. This article addresses a plane beam signal ground penetrating radar array observation method based on high radiation power gain. The transmitting antenna array simultaneously excites the pulse signal with the same center frequency. All the transmitted signals interfere with each other at the near surface to form a plane beam signal, and the electromagnetic energy is superimposed mutually to increase the radiation power. We applied the plane beam signal ground penetrating radar array method to different geological models constructed by the finite difference time-domain (FDTD) algorithm for numerical simulation in this research. Since there are various offsets in the array ground penetrating radar observation method, we introduce a composite frequency shift-perfect matching layer (CFS-PML) based on the recursive convolution method as the absorbing boundary condition. It eliminates the problem of secondary refection caused by the angle variation of the incident wave. The research result shows that the plane beam signal illuminates the target uniformly in space, can eliminate the discontinuity in profile data caused by the directivity of the antenna, improve the stability and quality of the echo signal, and enrich the target response parameters.