Boundary electric impedance. Medical search. Frequent questions

Ming's particular expertise and the core theme underlying his research is probing the 'electrical microstructure' and defect chemistry of materials (mainly metal oxides) using various electrical characterisation techniques, particularly Impedance Spectroscopy. (nottingham.ac.uk)
Ming's specialised in separating contributions to conductivity and permittivity from different regions (grains, grain boundaries, sample-electrode non-ohmic interfaces, surface layers, etc.) and identifying the nature of charge carriers (electrons, holes, ions, etc.) using Impedance Spectroscopy. (nottingham.ac.uk)
Fundamentals of Impedance Spectroscopy (J.Ross Macdonald and William B. Johnson). (typeset.io)
1.1.2 The Basic Impedance Spectroscopy Experiment. (typeset.io)
The oxide-ion conductivity was estimated to be 1.03(8) × 10 -5 S cm -1 at 1073 K. The total electrical conductivity and impedance spectroscopy measurements of this Ca 3 Ga 4 O 9 sample indicated that the bulk conductivity was much higher than the grain-boundary conductivity and that the total conductivity was equivalent to the bulk conductivity. (elsevierpure.com)
Impedance spectroscopy also revealed a strong modification of the signal assigned to grain boundaries, which evidenced that impurities partially migrated during the sintering step. (hal.science)

An algorithm is developed for electrical impedance tomography (EIT) of finite cylinders with general cross-sectional boundaries and translationally uniform conductivity distributions. (metu.edu.tr)
Dramatic influence of A-Site nonstoichiometry on the electrical conductivity and conduction mechanisms in the perovskite oxide Na0.5Bi0.5TiO3 Chemistry of Materials. (nottingham.ac.uk)
Such small compositional variations, although difficult to detect accurately by common chemical techniques, can induce significant changes in electrical conduction mechanism and conductivity as well as complex electrical inhomogeneity in a sample. (nottingham.ac.uk)
In an electrical impedance tomography system, the voltages measured in the peripheral boundaries have a non-linear equation with the electrical conductivity distribution. (sciopen.com)
Electrical impedance tomography, EIT, is an imaging modality in which the internal conductivity distribution of an object is reconstructed based on voltage measurements on the boundary. (mcmaster.ca)
To date, a coupled finite element model that accounts for the temperature-dependent electrical conductivity changes has not been developed for ablation type devices. (biomedcentral.com)
The results of four finite element models are compared: constant electrical conductivity without tissue perfusion, temperature-dependent conductivity without tissue perfusion, constant electrical conductivity with tissue perfusion, and temperature-dependent conductivity with tissue perfusion. (biomedcentral.com)
The data demonstrate that significant errors are generated when constant electrical conductivity is assumed in coupled electrical-heat transfer problems that operate at high temperatures. (biomedcentral.com)
P. Kügler, Identification of a temperature dependent heat conductivity from single boundary measurements , SIAM J. Num. (aimsciences.org)

His work in medical imaging has centered on the development of algorithms and devices for measuring and displaying the electrical state of the interior of a body from measurements made on the body's exterior. (rpi.edu)
Inference of Boundary Data from Magnetic Measurements of Accelerator Magnets. (tu-darmstadt.de)
Electrical impedance tomography (EIT) is a functional imaging technique in which cross-sectional images of structures are reconstructed based on boundary trans-impedance measurements. (oulu.fi)
Owing to the periodicity (i.e. sparsity in frequency domain) of breathing and other physiological variations that may be reflected in EIT boundary measurements, data dimensionality may be reduced efficiently at the time of sampling using compressed sensing techniques. (oulu.fi)
The global impedance data (i.e. sum of all 544 measurements in each frame) was used in the subsequent studies. (oulu.fi)
Based on electrical measurements from electrodes placed around the boundary of a body, electrical impedance tomography (EIT) is an imaging procedure that recovers the spatial distribution of the conductivities in the interior of a body. (hal.science)

3.2.1.7 Effects of Connections and Input Impedance. (typeset.io)
Smith chart, input impedance and matching with single stubs. (uaeu.ac.ae)
Use the circuit-parameter (RLCG) model of transmission lines (TL) to solve for TL voltages and currents, and compute TL input impedance, standing wave ratio (SWR), and power. (uaeu.ac.ae)

In this study, we investigated the feasibility of a monopolar injection needle and lock-in amplifier (LIA)-based impedance measurement system for detecting the tissue type where the needle tip is located. (mdpi.com)
Impedance Measurement Techniques (Michael C. H. McKubre and Digby D. Macdonald). (typeset.io)
Commercially Available Impedance Measurement Systems (Brian Sayers). (typeset.io)
3.2.1 Electrochemical Impedance Measurement Systems. (typeset.io)
3.2.2 Materials Impedance Measurement Systems. (typeset.io)
3.2.2.2 Measurement of Low Impedance Materials. (typeset.io)
3.2.2.3 Measurement of High Impedance Materials. (typeset.io)

10] M. Costabel, E. Stephan, A direct boundary integral equation method for transmission problems, J. Math. (ucm.es)

Nonstationary phase boundary estimation in electrical impedance tomography using unscented Kalman filter. (uni-trier.de)
3] H.T. Banks, F. Kojima, W.P. Winfree, Boundary estimation problems arising in thermal tomography, Inverse Probl. (ucm.es)

After illustrating the techniques in time-harmonic acoustic problems with different boundary conditions and in electrical impedance tomography problems with continuous Neumann conditions, we extend the hybrid method for a realistic model in tomography where the boundary conditions are given at a discrete set of electrodes. (projecteuclid.org)
The only requirement placed upon the numerical Stokes solver is that boundary conditions of Dirichlet, Neumann and Robin types can be implemented. (bas.ac.uk)
Signorini problems model phenomena in which a known or unknown portion of the boundary is subjected to alternating Dirichlet and Neumann boundary conditions. (ucy.ac.cy)
Application of the same technique to the impedance tomography problem for a monotonic non-linear inclusion yields a characterization of the inclusion's support from the non-linear Neumann-to-Dirichlet operator. (aimsciences.org)

Ill-posed inverse boundary value problems are usually approached as problems of inference under a given set of boundary observations. (ucy.ac.cy)
We propose the use of the collocation Trefftz method for the solution of inverse geometric problems and, in particular, the determination of the boundary of a void. (ucy.ac.cy)
We study inverse problems for non-linear penetrable media in the context of scattering theory and impedance tomography. (aimsciences.org)
N. Grinberg and A. Kirsch, The linear sampling method in inverse obstacle scattering for impedance boundary conditions , J. Inverse Ill-Posed Probl. (aimsciences.org)

Through a process called acoustic-electric conversion, the transducer transforms the sound energy into electrical energy. (medscape.com)

This paper deals with the first and second order derivations of the surface impedance boundary conditions (IBC) applied to model such a metamaterial, which is equivalent to a bounded ground with a low negative permittivity. (jpier.org)
11. Leontovich, M. A., "Approximate boundary conditions for the electromagnetic field on the surface of a good conductor," Investigations Radiowave Propagation Part II , Academy of Sciences, 1978. (jpier.org)
In the present study, data obtained from a vast number of experimentally verified finite element simulation results is used for a metal forming process to develop a digitally-enhanced lubricant evaluation approach, by precisely representing the tribological boundary conditions at the workpiece/tooling interface, i.e., complex loading conditions of contact pressures, sliding speeds and temperatures. (imperial.ac.uk)
Artificial boundary conditions and domain truncation in electrical impedance tomography. (rpi.edu)
therefore the axial variation of the boundary conditions and also the potential field are expanded in Fourier series. (metu.edu.tr)
Conditions at media interfaces (boundary conditions). (cvut.cz)
2.1.4 Interfaces and Boundary Conditions. (typeset.io)
The questions that we have to better consider are how low in frequency we can go with this interface and which boundary conditions we should use. (comsol.com)
With respect to the boundary conditions, we know that the skin depth of the metal is very small over most of the frequency range. (comsol.com)
In terms of the excitation boundary conditions, the connection between the coaxial transmission line and the source is modeled via the Lumped Port boundary condition, of type Coaxial Cable , with the Source type set to Power . (comsol.com)
In terms of the setup, we need to be aware of the boundary conditions of our model. (comsol.com)
Apply EM boundary conditions and solve for normal wave incidence at boundary interface between two and three different dielectric media. (uaeu.ac.ae)

Electrical impedance tomography is a new technology in non-invasive imaging in which the image of the inner part of conductive bodies is reconstructed by the arrays of external electrodes that are connected on the periphery of the object. (sciopen.com)
As the electrical potential moves past the first of the two paired electrodes, that electrode becomes negative with respect to the second. (medscape.com)

This paper reviews the principles of Electrical Impedance Tomography (EIT), different types of current patterns and reconstruction algorithms to assess its potential in medical imaging. (ijsce.org)

This justifies us starting with the Impedance boundary condition and not modeling the electromagnetic fields inside of the metal domains . (comsol.com)

19] T. Hohage, F.-J. Sayas, Numerical approximation of a heat diffusion problem by boundary element methods using the Laplace transform, Numer. (ucm.es)
Two numerical methods are proposed to solve the electric impedance tomography (EIT) problem in a domain with arbitrary boundary shape. (jpier.org)
Impedance imaging of real objects or tissue phantoms with different current injection methods is also essential for better assessment of the biomedical EIT systems. (ijsce.org)
Design Methods for Reducing Failure Probabilities with Examples from Electrical Engineering. (tu-darmstadt.de)
However, these methods, including the finite element and boundary element methods, can require a prohibitively large number of elements as the wavelength becomes progressively shorter. (worktribe.com)

Characterization of impedance and wakefields of accelerator devices in the short bunch limit and beam dynamics effects for the CLIC Damping Rings. (tu-darmstadt.de)
M. Brühl, Explicit characterization of inclusions in electrical impedance tomography , SIAM J. Math. (aimsciences.org)

Finally, corrosion tests undertaken in liquid sodium at 500°C showed that the pellets were fragilized by the presence of silicon or high zirconium contents, possibly through the formation of Na2MO3 ternary oxides at the grain boundaries. (hal.science)

Few finite element models (FEM) have been developed to describe the electric field, specific absorption rate (SAR), and the temperature distribution surrounding hepatic radiofrequency ablation probes. (biomedcentral.com)

Mammography Phantom Studies Using 3D Electrical Impedance Tomography with Numerical Forward Solver. (uni-trier.de)

If the power dissipation is known (the difference between the input power and the output power), then measuring the case temperature rise above ambient determines the thermal impedance. (electronicspecifier.com)
If the heat transfer co-efficient is poor, then the dissipated power will cause a greater increase in the case temperature and the thermal impedance will be higher. (electronicspecifier.com)
Some heat will be conducted away via the electrical connections to the PCB tracks, so some temperature derating graphs given in the datasheets are accurate only if the PCB layout information is followed. (electronicspecifier.com)
Testing provides accurate, temperature-based data and information for datasheets, such as thermal impedance and maximum case temperature figures, efficiency vs load tables and temperature derating graphs for standard parts and those with a heatsink option. (electronicspecifier.com)

In this review, Resistivity images are reconstructed from the boundary data using Electrical Impedance Tomography and Diffuse Optical Tomography Reconstruction Software (EIDORS). (ijsce.org)
Thus, a limiting factor in high temporal resolution, 3D and fast EIT is the handling of the volume of raw impedance data produced for transmission and its subsequent storage. (oulu.fi)
To the best of our knowledge, no other study has evaluated the applicability of compressive sensing techniques on raw boundary impedance data in EIT. (oulu.fi)
The image reconstruction process is performed by injecting a precise electric current to the peripheral boundaries of the object, measuring the peripheral voltages induced from it and processing the collected data. (sciopen.com)
J. R. Cannon, Determination of the unknown coefficient $k(u)$ in the equation $\nabla k(u) \nabla u = 0$ from overspecified boundary data , J. Math. (aimsciences.org)

electrical impedance) of the internal parts of the target object is reconstructed. (sciopen.com)

One of the problems in Electrical Impedance Tomography (EIT) is the ill-possed problem occurred in the reconstruction process. (omicsonline.org)

For example, a completely new family of oxide ion conductors have been recently discovered through studying the electrical conduction mechanisms in a perovskite oxide piezoelectric material Na 1/2 Bi 1/2 TiO 3 (Nat. (nottingham.ac.uk)

As shown here, a simplification in the expression of the surface impedance is possible in the case of a planar and homogeneous surface. (jpier.org)

In short, the conductive materials should not be thought of as grounded, but instead as conductive surfaces of low impedance. (comsol.com)
In this study, we proposed a modified penalization formulation using the shifted sigmoid function for the interpolation of the electric permittivity of conductive materials and applied it to microwave structural design through the phase field design method. (elsevierpure.com)

Floating boundary algorithm and histogram abnormal prompt function. (contechealth.com)

There is a great interest to synthesize ferroelectric ceramics both with fine grain size and significant electric properties. (researchgate.net)

By introducing an effective surface current and a surface impedance, the losses on the interconnects can be easily included in UA-FWLIS by adding an extra term to the reaction elements. (arizona.edu)

The radius of the inner conductor is 0.25 mm, and the inside radius of the outer conductor is 0.75 mm, forming a low-loss coaxial transmission line of 50 Ω impedance. (comsol.com)
The outer conductor of the coax is electrically connected to the cavity walls via the Perfect Electric Conductor boundary condition, which represents an electrical connection without loss. (comsol.com)
The condition is applied at the annular boundary between the inner and outer conductor. (comsol.com)
In this paper, we incorporate the surface impedance boundary condition into a MoM-based Full-Wave Layered Interconnect Simulator (UA-FWLIS) to make it capable of handling conductor losses. (arizona.edu)
To avoid the expensive fine meshing and computing process, the condition of the perfect electrical conductor (PEC) or the impedance boundary condition has been generally used in FEA based topology optimization. (elsevierpure.com)

Topology optimization, also known as layout optimization, involves multiple physics encompassing structural, thermal, fluidic electrical and electromechanical systems including coupled phenomena such as solids and fluids as in convective cooling systems, aerodynamical systems, electronics, actuators and motors. (metu.edu.tr)
2] H.T. Banks, F. Kojima, Boundary shape identification problems in two-dimensional domains related to thermal testing of materials, Quart. (ucm.es)
For true convection cooling operation, the thermal impedance has to be determined in a draught-free environment, as the air movement can influence the result. (electronicspecifier.com)
Thermal impedance is dependent on the efficiency with which heat is transferred to the surrounding fluid (e.g air). (electronicspecifier.com)
For most applications, the convection cooling thermal impedance figure is the most useful because this corresponds to the way that converters are soldered onto a circuit board and the heat dissipated inside the converter is then spread by free air convection cooling. (electronicspecifier.com)
Recom has its own in-house wind tunnel to accurately measure the thermal impedance of our products with forced cooling. (electronicspecifier.com)

Applications of this problem include Electrical resistivity tomography in geophysics and Electrical impedance tomography in medical imaging. (wikipedia.org)

Another major breakthrough was the solution of the boundary rigidity problem in two dimensions with Leonid Pestov and in higher dimensions with Plamen Stefanov and András Vasy. (wikipedia.org)
We give a detailed analysis of strengths and weaknesses of LF-SOM through comparisons with mentioned SOM and NFFT-SOM in solving EIT problem in a domain with arbitrary boundary shape. (jpier.org)

After positioning the monopolar injection needle tip into the dermis, hypodermis, or muscle layer of pork tissue, the electrical impedance was measured in the frequency range of 10 Hz to 10 kHz. (mdpi.com)
Once the probes are positioned, radiofrequency energy is delivered through the probe, into surrounding tissue, and to an electrical ground pad that is applied to the skin of the patient. (biomedcentral.com)

For a frequency-domain model, using the Circuit type is functionally identical to using a Lumped Element feature with a frequency-dependent impedance that is User defined . (comsol.com)

That allows to have a first order impedance boundary condition substituted for the required second order impedance boundary condition. (jpier.org)
Philippe Pouliguen, "Suitable Impedance Boundary Condition Applied to the Enhancement of the Electric Field Radiated by a High Frequency Surface Wave Radar," Progress In Electromagnetics Research C , Vol. 85, 117-128, 2018. (jpier.org)
The Lumped Port boundary condition models a connection to a lossless transmission line extending to infinity, and adding an excitation to the Lumped Port implies a source at infinity sending a signal down the line and into the modeled domain. (comsol.com)
In practice, the heat transfer co-efficient typically changes abruptly at a boundary condition when the air flow over the converter transitions from laminar to turbulent flow. (electronicspecifier.com)

This study is aimed to propose an absolute boundary potential to adjacent method. (omicsonline.org)
The result showed that adjacent method with absolute boundary potential give the better result compared to the use of relative boundary potential. (omicsonline.org)
More accurate FEM meshes should lead to more accurate thoracic electrical impedance tomography (EIT) images.Approach.The method was evaluated on an iPhone®that utilized an app called Heges, to obtain 3D scans (colored, surface triangulations), a custom belt, and custom open-source software developed to produce the subject-specific meshes. (bvsalud.org)

The remainder of the board is not modeled, and the traces are transmission lines of known impedance. (comsol.com)
With respect to the excitation of this model, we want to simulate four transmission lines of known impedances connected between the traces and ground plane. (comsol.com)

12 ] tested a different approach that employed two-time-domain reflectometry (TDR) probes placed directly into the mineral soil and at the boundary of the layer and the surface of the mineral soil. (hindawi.com)
The topic is also known as: mechanical surface impedance. (typeset.io)

Use the Smith Chart graphical tool in TL analysis, and apply TL concepts and Smith chart in the design and analysis of some TL applications (TL transformer, single stub, and impedance matching circuits). (uaeu.ac.ae)

Along with the geometric lumped element information, we need to specify the frequency-dependent impedance of the element. (comsol.com)

FBARs are highly complex devices and are challenging to design since there are physical parameters (i.e. geometry and materials) as well as electrical properties to consider. (ieee.org)

Pulmonary perfusion measured by means of electrical impedance tomography. (shengsci.com)
Electrical impedance tomography (EIT) is a recent imaging technique based on electrical impedance, offering the possibility of measuring pulmonary perfusion. (shengsci.com)

We can switch between the built-in options for a User defined , Capacitor , Inductor , Parallel LC , Series LC , Parallel RLC , and Series RLC equivalent impedance. (comsol.com)

Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. (stackexchange.com)

1.1.4 Impedance-Related Functions. (typeset.io)

it is used to integrate the electric field and evaluate the electric potential drop across the device. (comsol.com)

Anatomy1

Organisms1

Analytical, Diagnostic and Therapeutic Techniques and Equipment4

Phenomena and Processes2

SPECTROSCOPY6

Conductivity9

Measurements6

Input Impedance3

Measurement7

Integral equation1

Estimation2

Neumann4

Inverse4

Acoustic1

Conditions12

Electrodes2

Algorithms1

Electromagnetic1

Methods5

Characterization2

Oxides1

Finite element1

Solver1

Temperature4

Data5

Object is reconstructed1

Reconstruction1

Conduction1

Planar1

Conductive2

Algorithm1

Grain size1

Interconnects1

Conductor5

Thermal6

Resistivity1

Problem2

Tissue2

Frequency Domain1

Condition4

Method3

Transmission lines2

Surface2

Circuits1

Dependent1

Parameters1

Perfusion2

Equivalent1

Engineering1

Functions1

Device1