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An approach based on ANFIS and input selection procedure for microwave characterization of dielectric materials

SADOU, Hakim | HACIB, Tarik | AÇIKGÖZ, Hulusi | LE BIHAN, Yan | MEYER, Olivier | MEKIDECHE, Mohamed Rachid

Purpose: The principle of microwave characterization of dielectric materials using open-ended coaxial line probe is to link the dielectric properties of the sample under test to the measurements of the probe admittance (Y(f) = G(f)+ jB(f)). The purpose of this paper is to develop an alternative inversion tool able to predict the evolution of the complex permittivity (ε = ε′ – jε″) on a broad band frequency (f from 1 MHz to 1.8 GHz). Design/methodology/approach: The inverse problem is solved using adaptive network based fuzzy inference system (ANFIS) which needs the creation of a database for i ...Daha fazlası

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Microwave coaxial antenna for cancer treatment: Reducing the backward heating using a double choke

AÇIKGÖZ, Hulusi | MITTRA, Raj

In this paper, we focus on the so-called backward heating problem, which appears when coaxial-type antennas are used to treat certain types of cancers. The aim of this study is to reduce the surface currents propagating along the outer conductor of the antenna that lead to a higher Specific Absorption Rate (SAR) and overheat the healthy tissues. Our study shows that the use of a double-choke can lead to a lower SAR compared to the case of a single one. We also demonstrate that the use of a periodic structure does not help to further improve the SAR-level along the antenna. © 2015 The Institute ...Daha fazlası

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Electromagnetic Acoustic Transducer for cracks detection in conductive material

BOUGHEDDA, Houssem | HACIB, Tarik | CHELABI, Mohamed | AÇIKGÖZ, Hulusi | LE BIHAN, Yan

This paper is concerned with the characterization methodologies of defects in conducting materials by an Electromagnetic Acoustic Transducer (EMAT) testing system. It has been developed to create a virtual environment for Non-Destructive Testing (NDT) before implementing it in real, to study the change effect on the defect geometry at the signal received. EMAT is a new technology, which provides a noncontact process of testing materials compared to ultrasonic testing technique. This work is based on the simulation of two-dimensional numerical model, using Finite Element Method, (FEM) like a si ...Daha fazlası

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A Novel Microwave Coaxial Slot Antenna for Liver Tumor Ablation

AÇIKGÖZ, Hulusi | TÜRER, İbrahim

This paper is on the effect of a T-ring shape structure to enhance the capability of a microwave coaxial slot antenna (MCA) in the treatment of liver cancer. The MCA is composed of an interstitial coaxial line that is enclosed in a catheter. The T-ring shape structure is wrapped on the outer conductor of the MCA. Thanks to the new structure, the backward heating problem appearing in many coaxial antennas is reduced and the generated heat in front of the slot is higher than those for a classical MCA. © 2014, Tarbiat Modares University. All rights reserved.

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Predictors Generation by Partial Least Square Regression for microwave characterization of dielectric materials

SADOU, Hakim | HACIB, Tarik | LE BIHAN, Yan | MEYER, Olivier | AÇIKGÖZ, Hulusi

In this paper, the microwave characterization of dielectric materials using open-ended coaxial line probe is proposed. The measuring cell is a coaxial waveguide terminated by a dielectric sample. The study consists in extracting the real and imaginary part of the relative dielectric permittivity (ε = ε′-jε’’) of the material under test from the measurements of the probe admittance (Ymes(f) = Gmes(f)+jBmes(f)) on a broad band frequency (f between 1 MHz and 1.8 GHz), hence a direct and inverse problems have to be solved. In order to build a database, the direct problem is solved using Finite Ele ...Daha fazlası

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Grafen Benzeri Malzeme ile Kanser Tedavisinde Kullanılan Mikrodalga Antenlerde oluşan Yüzey Akımlarının Azaltılması

YILMAZ, Adem | AÇIKGÖZ, Hulusi | UZMAN, Burak

Bu çalışmada, kanser tedavisindeki önemi hızla artan mikrodalga yönteminde karşılaşılan geriye doğru ısınma problemi incelenmiştir. Daha önce yaptığımız grafen tabanlı malzeme kullanarak yüzey akımının en aza indirilmesi çalışmalarının devamı niteliğinde olan bu çalışmada grafenli ve grafensiz eş eksenli yarık antenlerin dış iletkeninde oluşan yüzey akımı gözlemlenmiştir. Doku içindeki SAR dağılımı ve buna bağlı olarak oluşan sıcaklık dağılımı incelenmiş ve grafen kaplanmış antenin yüzey akımını azaltmakta başarılı olduğu görülmüştür.

Erişime Açık

Microwave characterization using partial least square regression

SADOU, Hakim | HACIB, Tarik | LE BIHAN, Yan | AÇIKGÖZ, Hulusi | MEYER, Olivier

Inverse problems for determination of dielectric materials properties (complex permittivity) are usually solved by iterative methods using numerically based forward model. These methods are computationally expensive. In this paper, we propose a fast inversion model based on partial least square regression (PLSR). The idea is to build a model able to predict in real time the properties of the sample under test using measurements of admittance or reflexion coefficient of the propagating electromagnetic micro wave along the coaxial line. Numerical solution of the direct problem is made using Fini ...Daha fazlası

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Statistical analysis of 3D-printed flat GRIN lenses

AÇIKGÖZ, Hulusi | ARYA, Ravi Kumar | MITTRA, Raj

This paper presents the statistical analysis of a 3D printed flat lens by using the Polynomial Chaos Expansion (PCE) analysis technique. The flat lens is fabricated using the 3D printing technology and is based on the grading-index (GRIN) approach. It is composed of several concentric rings with graded relative permittivity, made of a single material with different air holes-host material volume ratio. We show that the hole size can have significant effect on the performance of the lens, especially on the focal distance. PCE analysis enables us also to determine the impact of each individual r ...Daha fazlası

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