We explain how to build invisible isotropic conductivity perturbations of the unit conductivity in the framework of the point electrode model for two-dimensional electrical impedance tomography. The theoretical approach, based on solving a fixed point problem, is constructive and allows the implementation of an algorithm for approximating the invisible perturbations. The functionality of the me...

A short review of current methods for damage detection and failure prevention in complex machinery is first presented. Two main classes are identified: (a) detailed inspection through machinery strip-down and minute examination with a variety of scanning methods, and (b) in-situ health monitoring using passive and active sensors. The emergence of new in-situ sensor techniques based on the activ...

Abstract: Plasma processing is used in a variety of industrial systems, including semiconductor manufacture (deposition and etching) and accurate control of the impedance matching network is vital if repeatable quality is to be achieved at the manufacturing process output. Typically, impedance matching networks employ series (tune) and parallel (load) capacitors to drive the reflection coeffici...

The relationship between the shape of the ascending aortic pressure wave form and aortic input impedance was studied in 18 patients who underwent elective cardiac catheterization but in whom no heart disease was found. Ascending aortic flow velocity and pressure were simultaneously recorded from a multisensor catheter with an electromagnetic velocity probe and a pressure sensor mounted at the s...

Introduction When analytically defining radio frequency circuits, a common approach incorporates admittance or impedance. Admittance, which is symbolized by Y, is defined in terms of conductance G and an imaginary susceptance component, jB. Admittance is often useful when defining parallel elements in a network and is expressed by the complex algebraic equation Y = G + jB. Impedance, the mathem...

BACKGROUND Bioelectrical impedance spectroscopy is applied to measure changes in tissue composition. The aim of this study was to evaluate its feasibility in measuring the fluid shift after thoracentesis in patients with pleural effusion. METHODS 45 participants (21 with pleural effusion and 24 healthy subjects) were included. Bioelectrical impedance was analyzed for "Transthoracic," "Foot to...

The longitudinal space charge and resistive wall impedances have been investigated in a smooth cylindrical beam pipe. At any point from the beam axis, we obtained an expression for the total impedance, which at the beam surface r=a for infinite pipe wall conductivity gives the expression for the total impedance that was derived by Zotter and Kheifets in studying the impedance of uniform beams i...

BACKGROUND Ventilatory pressures should target the range between the upper and lower inflection point of the pressure volume curve in order to avoid atelecto- and volutrauma. During high-frequency oscillatory ventilation (HFOV), this range is difficult to determine. Quadrant impedance measurement (QIM) has recently been shown to allow accurate and precise measurement of lung volume changes duri...

Impedance measurements have been widely used with the Nyquist plot to estimate the stability of interconnected power systems. Being a black-box method for equivalent and aggregated impedance estimation, its use for the identification of sub-components bandwidth is not a straightforward task. This paper proposes a simple method that will enable to identify the specific part of the equivalent imp...

The problem of electrical impedance between the skin and the electrode is an on-going challenge in bio-electronics. This is particularly true in the case of Electrical Impedance Tomography (EIT), which uses a large number of skin-contact electrodes and is very sensitive to noise. In the present article, contact impedance is measured and compared for a range of electrodes placed on the thorax of...