نتایج جستجو برای: permittivity

تعداد نتایج: 5151  

Journal: :Philosophical transactions. Series A, Mathematical, physical, and engineering sciences 2016
E Al Hosani M Soleimani

Multiphase flow imaging is a very challenging and critical topic in industrial process tomography. In this article, simulation and experimental results of reconstructing the permittivity profile of multiphase material from data collected in electrical capacitance tomography (ECT) are presented. A multiphase narrowband level set algorithm is developed to reconstruct the interfaces between three-...

2016
Lei Sun Xiaodong Yang Jie Gao

A generalized nonlocal effective medium theory is derived based on the transfer-matrix method to determine the nonlocal effective permittivity and permeability for the symmetric and periodic metal–dielectric multilayer metamaterials, with respect to both transverse-electric and transversemagnetic polarized light at arbitrary angle of incidence. The nonlocal effective permittivity and permeabili...

2014
Jochen Moll Thomas N. Kelly Dallan Byrne Mantalena Sarafianou Viktor Krozer Ian James Craddock

Conventional radar-based image reconstruction techniques fail when they are applied to heterogeneous breast tissue, since the underlying in-breast relative permittivity is unknown or assumed to be constant. This results in a systematic error during the process of image formation. A recent trend in microwave biomedical imaging is to extract the relative permittivity from the object under test to...

Journal: :Physical review letters 2012
Brian Edwards Nader Engheta

Electric displacement current is present in capacitors and optical waveguides; however, unlike the conduction current in metallic wires, it is not confined. Analogous to the contrast in conductivity between a metallic wire and the surrounding air, displacement-current wires based on near-zero permittivity media contain a large contrast in effective permittivity. As a variation on this idea, in ...

1991
Paul D. Domich James Baker-Jarvis Richard G. Geyer

This paper discusses optimization techniques for the determination of complex permittivity and permeability in transmission lines. The traditional theoretical model using scattering parameters is extended into a mathematical regression model that can be solved with widely accepted numerical techniques. This new model produces accurate primary mode results for the samples tested including nonmag...

2009
U. Katscher P. Karkowski T. Voigt

Introduction Tissue permittivity might serve as diagnostic parameter, e.g., for oncology [1]. However, the diagnostic use of the permittivity is significantly hampered by the lack of suitable methods to determine the permittivity in vivo. A possible approach for the determination of permittivity in vivo is given by analyzing the B1 map in the framework of standard MRI, called "Electric Properti...

Journal: :Bioelectrochemistry 2006
Kongshuang Zhao Wei Bai Hualing Mi

The dielectric spectroscopy of Anabaena 7120 protoplast suspensions has been investigated over the frequency range of 40 Hz-110 MHz. The protoplast suspensions showed a complicated dielectric dispersion consisting of at least four distinct sub-dispersions with the increasing frequencies due to the Maxwell-Wagner interfacial polarization. The double-shell model, in which an equivalent shell of t...

2003
Pikul Wanichapichart Sorawuth Bunthawin Kamnoon Kanchanapoom

Experiments were carried out on four cell types: Chlorella sp., Tetraselmis sp., and mesophyll protoplasts of Dendrobium and Lilium longiflorum. The speed of cell translation in between a pair of cylindrical electrodes was measured at different solution conductivities (σs). For each field frequency, the speed was plotted against the gradient of electric field squared to obtain the real part Re[...

2013
G. Behzadi L. Fekri

In this study, we reported the effect of frequency on the electrical parameter and permittivity of water samples using an invasive capacitive sensor. The measured capacitance, resistance and dissipation factor for distilled water, mineral water, tap water and salt water for different frequency is reported and results compared. Comparison of the measured capacitances for water samples shows a de...

2013
M. Y. Ismail M. Hashim W. N. Zaihasra

The emerging field of communications has increased the demand of electronically tunable reflectarray antennas. Substrate material properties play at1 important role in the design of reflectamy antennas. Variable permittivity materials such as liquid crystals and fenoelectrics have received great deal of attention due to their non-linear material properties. A comparative analysis behveen the pr...

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