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Purpose: To investigate whether the risk of peripheral nerve stimulation increases in the presence of bulky metallic prostheses implanted in a patient's body. Methods: A computational tool was used to calculate the electric field (E‐field) induced in a realistic human model due to the action of gradient fields. The calculations were performed both on the original version of the anatomical model and on a version modified through "virtual surgery" to incorporate knee, hip, and shoulder prostheses. Five exam positions within a body gradient coil and one position using a head gradient coil were simulated, subjecting the human model to the readout gradient from an EPI sequence. The induced E‐field in models with and without prostheses was compared, focusing on the nerves and all other tissues (both including and excluding the bones from the analysis). Results: In the nerves, the most pronounced increase in the E‐field (+24%) was observed around the knee implant during an abdominal MRI (Y axis readout). When extending the analysis to encompass all tissues (excluding bones), the greatest amplification (+360%) occurred around the knee implant during pelvic MRI (Z axis readout). Notable increases in E‐field peaks were also identified around the shoulder and hip implants in multiple scenarios. Conclusion: Based on the presented results, further investigations aimed at quantifying the threshold of nerve stimulation in the presence of bulky implants are desirable. [ABSTRACT FROM AUTHOR]

A major refurbishment of the toroidal complex of the RFX-mod device is in progress and it will include the removal of the Inconel vacuum vessel and a modification of the stainless steel supporting structure to be made vacuum-tight. The axisymmetric equilibrium control in RFX-mod was responsible for the control of the plasma current, horizontal and vertical position along with its stability and the plasma shape. The new implementation framework, both hardware and software, is described. The system has been fully reviewed and modified, if needed, for its prospective use in RFX-mod2. In order to run tests in an operation-like context, the updated system has also been implemented in the MARTe2 framework, to be deployed for the real-time applications of RFX-mod2. The results of the previous versions were reproduced and the cycle-time requirements were met. [ABSTRACT FROM AUTHOR]

This article describes a novel and accurate implementation of finite element method-boundary element method (FEM-BEM) coupling based on Argyris element (AE), for the $C^{1}$ solution of axi-symmetric magnetostatic problems in open boundary domains. The aim of the work is twofold: 1) to provide novel, easy, and accurate way to compute the basis functions that is strongly not affected by accuracy errors and 2) to give a clear mathematical and numerical description of the FEM-BEM coupling based on AE. The first goal is achieved by shifting to the origin the physical triangular elements and computing the basis function in the shifted coordinate system. Second, AE-based FEM-BEM coupling relies on the boundary integral equations (BIEs) for poloidal flux and its partial derivatives of both first and second order, accurately computed by combining the analytical formula based on elliptic integrals together with high degree Gaussian cubature. The application of the proposed method to an advanced plasma equilibrium magnetic configuration, typical of magnetic confinement fusion (MCF) (i.e., snowflake configuration), highlights that, even in case of coarse triangulation, satisfactory results can be achieved, and the error on the boundary conditions (BCs) is well below machine working precision. [ABSTRACT FROM AUTHOR]

The electromagnetic analysis of the superconducting multistrand cables used to manufacture magnets for fusion research is described. An analysis method is described, in which the cable represented as an equivalent lumped network, whose parameters are automatically computed starting from the cable geometrical data.

The aim of this article is to describe and model a sawtooth crash in RFX-mod2 and compute the eddy currents induced in the stabilizing shell surrounding the plasma for two alternative gap concepts and the subsequent error field. The sawtooth crash displacement of the plasma column is represented by a vacuum model coupled with a suitable magneto-quasi-static (MQS) volume integral (VI) formulation. [ABSTRACT FROM AUTHOR]

In this work, a surface current plasma model is coupled to a volume integral formulation for studying the interaction between tokamak tearing modes (TMs) and the machine metallic structures surrounding the plasma. By evaluating the passive response on a set of pickup probes, TMs’ amplitude is estimated. [ABSTRACT FROM AUTHOR]

The damping properties of NiTi elements produced through selective laser melting are investigated by tuning the process parameters. To this end, twelve parameters' sets are selected to fabricate fully‐dense NiTi specimens. Damping is evaluated through loss factor index, mechanical loading cycles (up to 104 cycles), solicitation frequency and strain amplitude. Results confirm that NiTi fabricated through selective laser‐beam melting is an excellent candidate to substitute conventional materials when used in the martensite phase. Furthermore, the selected process parameters enable specific damping performances that can be collected in damping maps which turn out to be practical tools for the fabrication of NiTi parts with tunable damping response. [ABSTRACT FROM AUTHOR]

In patients with moderate-to-severe Chronic Obstructive Pulmonary Disorder (COPD), pulmonary hyperinflation can occur at rest and increase during episodes of exacerbation. Among other mechanical constraints, changes in position and configuration of the diaphragm are also induced by increased end-expiratory lung volume. Both descent and flattening of diaphragm might damage the phrenic nerves by stretching their fibers. The study aimed to investigate the phrenic nerve conduction in COPD patients in stable conditions and during COPD exacerbation. In a group of 11 COPD patients without relevant comorbidities in stable conditions and subsequently in another group of 10 COPD patients during in-hospital COPD exacerbation and recovery, measurements of functional respiratory parameters and assessment of phrenic nerves motor conduction by bilateral electric stimulation were performed concurrently. Significant increase in phrenic nerves latency (p < 0.05), but similar amplitude of motor compound muscle action potential (cMAP) was observed in stable COPD patients vs. matched controls (p < 0.05). However, in COPD patients with resting pulmonary hyperinflation as reliably detected by substantial Inspiratory Capacity reduction (<80% pred.), the mean bilateral latency was longer vs. COPD patients without pulmonary hyperinflation (p < 0.02). During COPD exacerbation, in contrast with mean latency, the mean amplitude of phrenic nerves cMAP improved at discharge when compared with in-hospital admission (p < 0.05). In stable COPD patients the velocity of phrenic nerve conduction was impaired mostly in the presence of pulmonary hyperinflation, while during COPD exacerbation where dynamic pulmonary hyperinflation abruptly occurs, the reversible decrease of cMAP amplitude does suggest a temporary, acute axonal damage of phrenic nerves, potentially contributing to diaphragmatic dysfunction in these circumstances. [ABSTRACT FROM AUTHOR]

The partial element equivalent circuit (PEEC) method is applied to a frequency-sweep study for investigating the resonant modes of planar spiral resonators. A low-rank approximation algorithm, based on hierarchical matrices, is coupled to the method in order to reduce the computational effort due to the use of dense matrices. The partitioning of the matrices is carefully addressed in order to allow an efficient hierarchical off-diagonal low-rank structure of the system matrix. [ABSTRACT FROM AUTHOR]