This chapter introduces the finite element method (FEM) as a tool for solution of classical electromagnetic problems. Although we discuss the main points in the application of the finite element method to electromagnetic design, including formulation and implementation, those who seek deeper understanding of the finite element method should consult some of the works listed in the bibliography section.

Introduction to the Finite Element Method

An endoscopic bipolar forceps includes an elongated shaft having opposing jaw members at a distal end thereof. The jaw members are movable relative to one another from a first position wherein the jaw members are disposed in spaced relation relative to one another to a second position wherein the jaw members cooperate to grasp tissue therebetween. The forceps also includes a source of electrical energy connected to each jaw member such that the jaw members are capable of conducting energy through tissue held therebetween to effect a seal. A generally tube-like cutter is included which is slidably engaged about the elongated shaft and which is selectively movable about the elongated shaft to engage and cut tissue on at least one side of the jaw members while the tissue is engaged between jaw members.

Vessel sealer and divider

A monitoring system includes one or more wireless nodes forming a wireless mesh network; a user activity sensor including a wireless mesh transceiver adapted to communicate with the one or more wireless nodes using the wireless mesh network; and a digital monitoring agent coupled to the wireless transceiver through the wireless mesh network to request assistance from a third party based on the user activity sensor.

Mesh network personal emergency response appliance

A heart monitoring system for a person includes one or more wireless nodes; and a wearable appliance in communication with the one or more wireless nodes, the appliance monitoring vital signs.

Health monitoring appliance

An electrosurgical system is disclosed. The electrosurgical system includes an electrosurgical generator adapted to supply electrosurgical energy to tissue. The electrosurgical generator includes impedance sensing circuitry which measures impedance of tissue, a microprocessor configured to determine whether a tissue reaction has occurred as a function of a minimum impedance value and a predetermined rise in impedance, wherein tissue reaction corresponds to a boiling point of tissue fluid, and an electrosurgical instrument including at least one active electrode adapted to apply electrosurgical energy to tissue.

Vessel sealing system

Electrical capacitance tomography (ECT) attempts to image the permittivity distribution of an object by measuring the electrical capacitances between sets of electrodes placed around its periphery. Image reconstruction in ECT is a nonlinear and ill-posed inverse problem. Although reconstruction techniques based on a linear approximation are fast, they are not adequate for all cases. In this paper, we study the nonlinearity of the inverse permittivity problem of ECT. A regularized Gauss-Newton scheme has been implemented for nonlinear image reconstruction. The forward problem has been solved at each iteration using the finite element method and the Jacobian matrix is recalculated using an efficient adjoint field method. Regularization techniques are required to overcome the ill-posedness: smooth generalized Tikhonov regularization for the smoothly varying case, and total variation (TV) regularization when there is a sharp transition of the permittivity have been used. The reconstruction results for experimental ECT data demonstrate the advantage of TV regularization for jump changes, and show improvement of the image quality by using nonlinear reconstruction methods.

https://iopscience.iop.org/article/10.1088/0957-0233/16/10/014/pdf

Nonlinear image reconstruction for electrical capacitance tomography using experimental data

An infusion system (110) has a capability to monitor infusion complications such as extravasation, tissue necrosis, infiltration, phlebitis, and blood clots. The infusion system (100) has at least partially transparent flexible film barrier dressing (122) in a flexible membrane that incorporates a plurality of sensors capable of detecting tissue condition and a control unit capable of coupling to the film barrier (122) dressing that monitors signals from the sensors (120). A device is capable of executing non-invasive physiological measurements to characterize physiologic information from cross-sectional surface and subcutaneous tissue to detect the presence or absence of tissue conditions such as infiltration or extravasation during intravascular infusion. In some examples, the device utilizes depth-selective methods to sense, detect, quantify, monitor, and generate an alert notification of tissue parameters.

Tissue monitoring system for intravascular infusion

An impedance model of tissue is useful for describing conductivity reconstruction in tissue. Techniques for determining and mapping conductivity distribution in tissue supply useful information of anatomical and physiological status in various medical applications. Electrical Impedance Tomography (EIT) techniques are highly suitable for analyzing conductivity distribution. Electrical characteristics of tissue include resistive elements and capacitive elements. EIT techniques involve passing a low frequency current through the body to monitor various anatomical and physiological characteristics. The system can interrogate at multiple frequencies to map impedance. Analytical techniques involve forward and inverse solutions to boundary value analysis to tissue characteristics.

Conductivity reconstruction based on inverse finite element measurements in a tissue monitoring system

In this article the Tomographic Iterative GPU-based Reconstruction (TIGRE) Toolbox, a MATLAB/CUDA toolbox for fast and accurate 3D x-ray image reconstruction, is presented. One of the key features is the implementation of a wide variety of iterative algorithms as well as FDK, including a range of algorithms in the SART family, the Krylov subspace family and a range of methods using total variation regularization. Additionally, the toolbox has GPU-accelerated projection and back projection using the latest techniques and it has a modular design that facilitates the implementation of new algorithms. We present an overview of the structure and techniques used in the creation of the toolbox, together with two usage examples. The TIGRE Toolbox is released under an open source licence, encouraging people to contribute.

/pdf/tigre-a-matlab-gpu-toolbox-for-cbct-image-reconstruction-108luuh166.pdf

TIGRE: A MATLAB-GPU toolbox for CBCT image reconstruction

Electrical capacitance tomography (ECT) is a relatively mature non-invasive imaging technique that attempts to map dielectric permittivity of materials. ECT has become a promising monitoring technique in industrial process tomography especially in fast flow visualization. One of the most challenging tasks in further development of ECT for real applications are the computational aspects of the ECT imaging. Recently, 3D ECT has gained interest because of its potential to generate volumetric images. Computation time of image reconstruction in 3D ECT makes it more difficult for real time applications. In this paper we present a robust and computationally efficient 4D image reconstruction algorithm applied to real ECT data. The method takes advantage of the temporal correlation between 3D ECT frames to reconstruct movies of dielectric maps. Image reconstruction results are presented for the proposed algorithms for experimental ECT data of a rapidly moving object.

/pdf/four-dimensional-electrical-capacitance-tomography-imaging-1xuqe4xucb.pdf

Manuchehr Soleimani

Papers

Nonlinear image reconstruction for electrical capacitance tomography using experimental data

Tissue monitoring system for intravascular infusion

Conductivity reconstruction based on inverse finite element measurements in a tissue monitoring system

TIGRE: A MATLAB-GPU toolbox for CBCT image reconstruction

Four-Dimensional Electrical Capacitance Tomography Imaging Using Experimental Data