Coil Location Research Articles

Research on Fault Location of SF6 Circuit Breaker Relay Coil Based on Traveling-Wave Reflection Method

—The traveling wave-reflection method is proposed to locate the short circuit fault of the opening/closing coil of the circuit breaker, the capacitance and inductance matrix of the opening/closing coil are calculated by finite element simulation, and the wave impedance model of the coil is established based on ATP-EMTP. A low-voltage square wave pulse signal is injected into the head end of the winding to detect the characteristic curve of the reflected wave when an inter-turn short-circuit fault occurs. The generalized fractal dimension of reflection wave characteristic curve was calculated and its variation as the position of short circuit change was analysed. Compared with box dimension, the variation of information dimension and correlation dimension are more obvious, thus information dimension and correlation dimension are selected as inpus, and the evaluation model of inter-turn short circuit position is established based on probabilistic neural network.

A neurostimulator system for real, sham, and multi-target transcranial magnetic stimulation

Objective. Transcranial magnetic stimulation (TMS) is a clinically effective therapeutic instrument used to modulate neural activity. Despite three decades of research, two challenging issues remain, the possibility of changing the (a) stimulated spot and (b) stimulation type (real or sham) without physically moving the coil. In this study, a second-generation programmable TMS device with advanced stimulus shaping is introduced that uses a five-level cascaded H-bridge inverter and phase-shifted pulse-width modulation. The principal idea of this research is to obtain real, sham, and multi-locus stimulation using the same TMS system. Approach. We propose a two-channel modulation-based magnetic pulse generator and a novel coil arrangement, consisting of two circular coils with a physical distance of 20 mm between the coils and a control method for modifying the effective stimulus intensity, which leads to the live steerability of the target and type of stimulation. Main results. Based on the measured system performance, the stimulation profile can be steered ±20 mm along a line from the centroid of the coil locations by modifying the modulation index. Significance. The proposed system supports electronic control of the stimulation spot without physical coil movement, resulting in tunable modulation of targets, which is a crucial step towards automated TMS machines.

Receiver-Coil Location Detection in a Dynamic Wireless Power Transfer System for Electric Vehicle Charging.

Receiver position sensing is investigated in a dynamic wireless power transfer (DWPT) system for electric vehicle (EV) charging. Exploiting the peculiar behaviour of the resonator arrays input impedance, it is possible to identify the position of the receiver coil by exciting the first array resonator with a signal at a proper frequency and measuring the resulting current. An analytical expression of the input impedance of the resonator array coupled with the EV receiver coil placed in a generic position is provided; its sensitivity to different circuit parameters is also analysed. The outline of a simple and effective algorithm for the localization of the EV is proposed and applied to a test case.

Genetic Algorithm for TMS Coil Position Optimization in Stroke Treatment.

Transcranial magnetic stimulation (TMS), a non-invasive technique to stimulate human brain, has been widely used in stroke treatment for its capability of regulating synaptic plasticity and promoting cortical functional reconstruction. As shown in previous studies, the high electric field (E-field) intensity around the lesion helps in the recovery of brain function, thus the spatial location and angle of coil truly matter for the significant correlation with therapeutic effect of TMS. But, the error caused by coil placement in current clinical setting is still non-negligible and a more precise coil positioning method needs to be proposed. In this study, two kinds of real brain stroke models of ischemic stroke and hemorrhagic stroke were established by inserting relative lesions into three human head models. A coil position optimization algorithm, based on the genetic algorithm (GA), was developed to search the spatial location and rotation angle of the coil in four 4 × 4 cm search domains around the lesion. It maximized the average intensity of the E-field in the voxel of interest (VOI). In this way, maximum 17.48% higher E-field intensity than that of clinical TMS stimulation was obtained. Besides, our method also shows the potential to avoid unnecessary exposure to the non-target regions. The proposed algorithm was verified to provide an optimal position after nine iterations and displayed good robustness for coil location optimization between different stroke models. To conclude, the optimized spatial location and rotation angle of the coil for TMS stroke treatment could be obtained through our algorithm, reducing the intensity and duration of human electromagnetic exposure and presenting a significant therapeutic potential of TMS for stroke.

Bipolar reasoning in feedback pathways

Instead of the conventional 0 and 1 values, bipolar reasoning uses −1, 0, +1 to describe double-sided judgements in which neutral elements are halfway between positive and negative evaluations (e.g., “uncertain” lies between “impossible” and “totally sure”). We discuss the state-of-the-art in bipolar logics and recall two medieval forerunners, i.e., William of Ockham and Nicholas of Autrecourt, who embodied a bipolar mode of thought that is eminently modern. Starting from the trivial observation that “once a wheat sheaf is sealed and tied up, the packed down straws display the same orientation”, we work up a new theory of the bipolar nature of networks, suggesting that orthodromic (i.e., feedforward, bottom-up) projections might be functionally coupled with antidromic (i.e., feedback, top-down) projections via the mathematical apparatus of presheaves/globular sets. When an entrained oscillation such as a neuronal spike propagates from A to B, changes in B might lead to changes in A, providing unexpected antidromic effects. Our account points towards the methodological feasibility of novel neural networks in which message feedback is guaranteed by backpropagation mechanisms endowed in the same feedforward circuits. Bottom-up/top-down transmission at various coarse-grained network levels provides fresh insights in far-flung scientific fields such as object persistence, memory reinforcement, visual recognition, Bayesian inferential circuits and multidimensional activity of the brain. Implying that axonal stimulation by external sources might backpropagate and modify neuronal electric oscillations, our theory also suggests testable previsions concerning the optimal location of transcranial magnetic stimulation's coils in patients affected by drug-resistant epilepsy.

Minimum-Norm Estimation of TMS-Activated Motor Cortical Sites in Realistic Head and Brain Geometry.

Navigated transcranial magnetic stimulation (nTMS) is a widely used tool for motor cortex mapping. However, the full details of the activated cortical area during the mapping remain unknown due to the spread of the stimulating electric field (E-field). Computational tools, which combine the E-field with physiological responses, have potential for revealing the activated source area. We applied the minimum-norm estimate (MNE) method in a realistic head geometry to estimate the activated cortical area in nTMS motor mappings of the leg and hand muscles. We calculated the MNE also in a spherical head geometry to assess the effect of the head model on the MNE maps. Finally, we determined optimized coil placements based on the MNE map maxima and compared these placements with the initial hotspot placement. The MNE maps generally agreed well with the original motor maps: in the realistic head geometry, the distance from the MNE map maximum to the motor map center of gravity (CoG) was 8.8 ± 4.6 mm in the leg motor area and 6.6 ± 2.5 mm in the hand motor area. The head model did not have a significant effect on these distances; however, it had a significant effect on the distance between the MNE CoG and the motor map ( ). The optimized coil locations were < 1 cm from the initial hotspot in 7/10 subjects. Further research is required to determine the level of anatomical detail and the optimal mapping parameters required for robust and accurate localization.

Experimental investigation on the Euler-type location and orientation algorithm using magnetic field and its gradient tensor

The magnetic source location has wide application prospects in the fields of space exploration, non-destructive testing, security monitoring and target tracking. A constrained Euler location algorithm is applied to the location of a small current-carrying multi-turn ring coil, which is the closed analytic form of the position solution. The error of position solution for the traditional Euler location algorithm is deduced analytically. An experimental device of three-axis fluxgate magnetometer (TAFM) cross-array is constructed. The interference of ambient magnetic field is filtered from the magnetic data by the digital band-pass filter, and the magnetic field of the multi-turn coil is restructured by the least-squares fitting. The Euler and constrained Euler location algorithms are compared with the numerical simulation and the experimental data, and the results show that the constrained Euler location precision of the location algorithm is better than the Euler one. And more, experimental tests verify that the relative error of position solution is less than 10% for the two location algorithms in the given distance range.

Generator stator windings ground fault diagnosis for generator–grid​ directly connected system of floating nuclear power plant

For floating nuclear power plants, the internal power system adopts the generator–grid directly connected structure. Generator ground fault diagnosis enables the protective device to adaptively determine the generator tripping control mode based on the fault degree, and shorten the troubleshooting time by fault location. To accurately calculate the ground fault current under different system operating modes, a real-time grounding capacitance parameters calculation method without injection devices is proposed based on third harmonic voltage. Using the fault component principle, the ground fault current is calculated including the fundamental and the third harmonic components. Through fuzzy membership function, the ground fault degree function is established including the ground fault current and the system overvoltage. It comprehensively reflects the damage degree of both the generator operating security and the system insulation security. According to the 60° phase-band distribution characteristic of the stator windings, a fault coil location method based on the windings’ electric potential distribution characteristics is proposed. PSCAD/EMTDC simulation results show that the proposed method has high computational accuracy.

S2198 Are Migrated Variceal Coils Amenable to Endoscopic Treatment?

Introduction: Embolization coil migration into the gastrointestinal tract is an extremely rare complication. Several case reports have described coil migration into the gastrointestinal tract after treatment of gastric varices, splenic artery pseudoaneurysm, and post-liver transplant. There is no standard of care for migrated coils, and treatment has ranged from conservative management to surgical/endoscopic removal. We report a rare case of coil migration into the stomach after direct intrahepatic portosystemic shunt (DIPS) and variceal coiling of gastric varices. Case Description/Methods: A 61-year-old man admitted with 3-week onset of epigastric pain. He has history of NASH cirrhosis complicated by bleeding esophageal and gastric varices status post coiling and embolization with DIPS in 2016. Pain was exacerbated by certain positions, and improved in the left lateral decubitus position. Pain was not related to food intake. Vitals were stable and labs were unremarkable at presentation.CT scan of abdomen and pelvis with IV contrast showed possible foreign body in the gastric lumen (Figure 1A). EGD showed migration of previous variceal coils into the gastric lumen, particularly around in the fundus and cardia (Figures 1B-C). Venogram was obtained to asses anatomy and coil location. This demonstrated complete occlusion of the previously embolized gastric varices. After the venogram, EGD was completed with successful removal of visibly migrated coils using small biopsy forceps (Figure 1D). No bleeding or complications occurred after the procedure. Although subsequent imaging showed remaining coils, there were significantly less compared to admission. The patient had intermittent resolution of his abdominal pain, but was readmitted several times afterwards for EGD removal of remaining coils. Discussion: Although etiology is unclear, the mechanism of variceal coil migration is likely related to fistula formation and inflammation within the gastric wall. In this case we attempted treatment endoscopically with removal of variceal coils with biopsy forceps. Successful removal of visualized coils alleviated abdominal pain, though it was temporary. An alternative treatment would be surgical intervention, however given risk of decompensation of cirrhosis and complications, it would be as a last resort. In the setting of successfully embolized vessels, we believe it is safe for endoscopic retrieval of the gastric coils in symptomatic patients.Figure 1.: (A) CT abdomen and pelvis showing metallic foreign body (red arrow) - coil migration from previous embolization. (B-D) Endoscopic images showing coils (yellow arrow) from previous IR intervention found in stomach fundus and cardia status post removal using small biopsy forceps.

Optimal Relay Coil Placement in Magnetic Resonant Coupling-Based Power Transfer

Wireless power transfer system based on magnetic resonant coupling (MRC-WPT) is widely used to prolong the lifetime of energy-limited devices for short-distance transmission. To maximize the harvested power for the three-coil MRC-WPT system, in this letter a novel optimization problem is proposed to determine the location of relay coil. Although this problem is non-convex, we still have been able to obtain the globally optimal solution in the form of roots of five degree polynomial. We also present a tight closed-form approximation for the optimal location of relay coil to gain analytical insights. Numerical results verify the global optimality claim and provide insights on the coil location for different system parameters. Lastly, it’s shown that the optimal relay location is closer to the destination coil.

A probabilistic transcranial magnetic stimulation localization method

Objective. Transcranial magnetic stimulation (TMS) can be used to safely and noninvasively activate brain tissue. However, the characteristic parameters of the neuronal activation have been largely unclear. In this work, we propose a novel neuronal activation model and develop a method to infer its parameters from measured motor evoked potential signals. Approach. The connection between neuronal activation due to an induced electric field and a measured motor threshold is modeled. The posterior distribution of the model parameters are inferred from measurement data using Bayes’ formula. The measurements are the active motor thresholds obtained with multiple stimulating coil locations, and the parameters of the model are the location, preferred direction of activation, and threshold electric field value of the activation site. The posterior distribution is sampled using a Markov chain Monte Carlo method. We quantify the plausibility of the model by calculating the marginal likelihood of the measured thresholds. The method is validated with synthetic data and applied to motor threshold measurements from the first dorsal interosseus muscle in five healthy participants. Main results. The method produces a probability distribution for the activation location, from which a minimal volume where the activation occurs with 95% probability can be derived. For eight or nine stimulating coil locations, the smallest such a volume obtained was approximately 100 mm3. The 95% probability volume intersected the pre-central gyral crown and the anterior wall of the central sulcus, and the preferred direction was perpendicular to the central sulcus, both findings being consistent with the literature. Furthermore, it was not possible to rule out if the activation occurred either in the white or grey matter. In one participant, two distinct activations sites were found while others exhibited a unique site. Significance. The method is both generic and robust, and it lays a foundation for a framework that enables accurate analysis and characterization of TMS activation mechanisms.

Evaluation of Heating Technique of Deformed Reinforcement Using High-Frequency Induction Heating System

To improve recycling quality, it is necessary to develop a demolition technology that can be combined with existing crushing methods that employ large shredding-efficient equipment. The efficient collection of bones in a segmentation dismantling method must be considered according to the procedure. Furthermore, there is a need for the development of partial dismantling technologies that enable efficient remodeling, maintenance, and reinforcement. In this study, we experimentally investigated the temperature-rise characteristics of reinforced concrete through partial rapid heating during high-frequency induced heating. Accordingly, the chemical and physical vulnerability characteristics of the reinforced concrete were verified by studying the thermal conduction on the surface of the rebars and the cracks caused by the thermal expansion pressure of the rebars. Furthermore, we aimed to verify the applicability of the proposed technology by specifying the vulnerability range of the reinforced concrete based on the heating range, as well as the appropriate energy consumption. We investigated the temperature rise and temperature distribution characteristics of the rebar surfaces based on diameter, length, bar placement conditions, heating distance, heating coil location, and output, using reinforced steel of grade SD345. Maximum powers of 5, 6, and 10 kW, and inductive heating were used to achieve satisfactory results.

Two-dimensional resistive MHD simulation of the optimized plasma formation in the spherical tokamaks

We present 2D global MHD simulation results of the optimized start-up scenarios for the spherical tokamak to maximize the ion heating energy determined by the value of the poloidal private flux during the merging start-ups. The series of simulations has successfully revealed the dependence of the poloidal private flux on the in-vessel poloidal coils’ separation length under the fixed amount of coils’ magnetic energy. The radial and azimuthal locations of the internal coils need to be optimized to maximize high private flux and consequently high ion heating energy. In the case of a two poloidal field (PF) coils system, the private flux and ion heating energy increase with the coils’ separation length. Installing two additional PF coils improves the private flux significantly, even if the coils’ separation length is short.

Targeting location relates to treatment response in active but not sham rTMS stimulation

BackgroundPrecise targeting of brain functional networks is believed critical for treatment efficacy of rTMS (repetitive pulse transcranial magnetic stimulation) in treatment resistant major depression. ObjectiveTo use imaging data from a “failed” clinical trial of rTMS in Veterans to test whether treatment response was associated with rTMS coil location in active but not sham stimulation, and compare fMRI functional connectivity between those stimulation locations. MethodsAn imaging substudy of 49 Veterans (mean age, 56 years; range, 27–78 years; 39 male) from a randomized, sham-controlled, double-blinded clinical trial of rTMS treatment, grouping participants by clinical response, followed by group comparisons of treatment locations identified by individualized fiducial markers on structural MRI and resting state fMRI derived networks. ResultsThe average stimulation location for responders versus nonresponders differed in the active but not in the sham condition (P = .02). The average responder location derived from the active condition showed significant negative functional connectivity with the subgenual cingulate (P < .001) while the nonresponder location did not (P = .17), a finding replicated in independent cohorts of 84 depressed and 35 neurotypical participants. The responder and nonresponder stimulation locations evoked different seed based networks (FDR corrected clusters, all P < .03), revealing additional brain regions related to rTMS treatment outcome. ConclusionThese results provide evidence from a randomized controlled trial that clinical response to rTMS is related to accuracy in targeting the region within DLPFC that is negatively correlated with subgenual cingulate. These results support the validity of a neuro-functionally informed rTMS therapy target in Veterans.

Analysis of a Possibility to Use Parallel Non-Twisted Stacks of HTS Tapes as Cable in High Current Conductor of Tokamak Toroidal Field Coils

Development of high current cable-in-conduit conductors (CICC) based on HTS tapes aimed for fusion magnets has started recently. The majority of the suggested CICC use as a HTS cable either, twisted stacks of HTS tapes (stacked technology), or some layers of tapes wrapped around a cylindrical core (CORC technology). An idea to use parallel non-twisted stacks of HTS tapes in a cable design is received skeptically by the fusion community, although such a cable design for tokamak toroidal field (TF) coils has some advantages over twisted ones. The twofold benefits is determined by parallel (deviation- θ <; 5°) orientation of toroidal field vector to surface of HTS tape and mutual orientation of background field and operating current vectors along conductor. Due to such orientation the critical current of tape-Ic(B;T) is considerably (in 5-6 times) higher, due to an anisotropy of HTS tape electro-physical properties. In addition a compressive force is oriented in the most beneficial direction. The main arguments against the non-twisted stacks in the cable design is a concern that the favorable condition described above are not the same in every location of TF coil, or that they will not be favorable in all modes of tokamak operation and the time of TF magnet charging is unreasonably long because of the screening current. The analysis carried out shows that the negative effect of screening currents decreases significantly due to a wavelike magnetic field distribution along conductor and that suggested design of HTS CICC is expected to be successful at any tokamak operation scenario.

Topology of eeg wave fronts

Whenever one attempts to comb a hairy ball flat, there will always be at least one tuft of hair at one point on the ball. This seemingly worthless sentence is an informal description of the hairy ball theorem, an invaluable mathematical weapon that has been proven useful to describe a variety of physical/biological processes/phenomena in terms of topology, rather than classical cause/effect relationships. In this paper we will focus on the electrical brain field-electroencephalogram (EEG). As a starting point we consider the recently-raised observation that, when electromagnetic oscillations propagate with a spherical wave front, there must be at least one point of the tangential components of the vector fields where the electromagnetic field vanishes. We show how this description holds also for the electric waves produced by the brain and detectable by EEG. Once located these zero-points in EEG traces, we confirm that they are able to modify the electric wave fronts detectable in the brain. This sheds new light on the functional features of a nonlinear, metastable nervous system at the edge of chaos, based on the neuroscientific model of Operational Architectonics of brain-mind functioning. As an example of practical application of this theorem, we provide testable previsions, suggesting the proper location of transcranial magnetic stimulation's coils to improve the clinical outcomes of drug-resistant epilepsy.

Evaluating transcranial magnetic stimulation (TMS) induced electric fields in pediatric stroke

Transcranial magnetic stimulation (TMS) is an increasingly popular tool for stroke rehabilitation. Consequently, researchers have started to explore the use of TMS in pediatric stroke. However, the application of TMS in a developing brain with pathologies comes with a unique set of challenges. The effect of TMS-induced electric fields has not been explored in children with stroke lesions. Here, we used finite element method (FEM) modeling to study how the electric field strength is affected by the presence of a lesion. We created individual realistic head models from MRIs (n = 6) of children with unilateral cerebral palsy due to perinatal stroke. We conducted TMS electric field simulations for coil locations over lesioned and non-lesioned hemispheres. We found that the presence of a lesion can strongly affect the electric field distribution. On the group level, the mean electric field strength did not differ between lesioned and non-lesioned hemispheres but exhibited a greater variability in the lesioned hemisphere. Other factors such as coil-to-cortex distance have a strong influence on the TMS electric field even in the presence of lesions. Our study has important implications for the delivery of TMS in children with brain lesions with respect to TMS dosing and coil placement.

Numerical simulation and experimental study of high-power thermal equilibrium inductively coupled plasma

Inductively coupled plasma generator is one of the core components of the near-space high-speed target plasma electromagnetic scientific experimental research device, which is often used to simulate high enthalpy and high speed plasma sheath environment. In order to study the discharge characteristics of inductively coupled plasma generator under high power, radio frequency and medium pressure, the numerical simulation and experiment are combined to study its internal heat transfer and flow characteristics in this paper. Based on the local thermodynamic equilibrium conditions, the numerical simulation of large-scale radio frequency and medium pressure inductively coupled plasma with a power of 100–400 kW is carried out through the multi-field coupling of flow, electromagnetic and temperature field, and verified by light intensity and spectrum experiment. The results show that the electromagnetic field distribution in the high-power thermal balance inductively coupled plasma generator is similar to that of the small- and medium-sized power plasma generator. The discharge energy dissipation occurs mainly in the area where the induction coil is located. The temperature of the inner wall of the quartz tube is higher at the coil location than in other areas, and the plasma has a ring-shaped high-temperature structure. The outer wall of the quartz tube is set to be the boundary condition of heat flux for simulating the temperature change of the quartz tube under cold blowing. This setting is in coincidence with factual situations. The wall temperature of the quartz tube at the entrance and at the induction coil section are found to be relatively high. When the large-size inductively coupled plasma generator works, an obvious return vortex is generated at the entrance due to the temperature difference and the electromagnetic pumping effect, and the exit velocity increases slightly with the increase of power. At the same time, the discharge experiment under the corresponding conditions shows that there is found a ring structure with bright edges and dark centers in the axial image of the argon discharge. Moreover, the emission spectrum of argon plasma is measured through the spectrum diagnosis system and the spatial distribution of the generator electron temperature is obtained. The light intensity of the discharge image and the electron temperature measured by the spectrum are found to be in comparative coincidence with the COMSOL simulation temperature result, demonstrating the validity of the numerical simulation results under thermodynamic equilibrium conditions. The numerical simulation results in this paper are also applicable to the optimization design and temperature resistance evaluation of the inductively coupled plasma generator.

Focality of the Induced E-Field Is a Contributing Factor in the Choice of TMS Parameters: Evidence from a 3D Computational Model of the Human Brain.

Transcranial magnetic stimulation (TMS) is a promising, non-invasive approach in the diagnosis and treatment of several neurological conditions. However, the specific results in the cortex of the magnitude and spatial distribution of the secondary electrical field (E-field) resulting from TMS at different stimulation sites/orientations and varied TMS parameters are not clearly understood. The objective of this study is to identify the impact of TMS stimulation site and coil orientation on the induced E-field, including spatial distribution and the volume of activation in the cortex across brain areas, and hence demonstrate the need for customized optimization, using a three-dimensional finite element model (FEM). A considerable difference was noted in E-field values and distribution at different brain areas. We observed that the volume of activated cortex varied from 3000 to 7000 mm3 between the selected nine clinically relevant coil locations. Coil orientation also changed the induced E-field by a maximum of 10%, and we noted the least optimal values at the standard coil orientation pointing to the nose. The volume of gray matter activated varied by 10% on average between stimulation sites in homologous brain areas in the two hemispheres of the brain. This FEM simulation model clearly demonstrates the importance of TMS parameters for optimal results in clinically relevant brain areas. The results show that TMS parameters cannot be interchangeably used between individuals, hemispheres, and brain areas. The focality of the TMS induced E-field along with its optimal magnitude should be considered as critical TMS parameters that should be individually optimized.

Differential Image Based Robot to MRI Scanner Registration with Active Fiducial Markers for an MRI-Guided Robotic Catheter System.

In magnetic resonance imaging (MRI) guided robotic catheter ablation procedures, reliable tracking of the catheter within the MRI scanner is needed to safely navigate the catheter. This requires accurate registration of the catheter to the scanner. This paper presents a differential, multi-slice image-based registration approach utilizing active fiducial coils. The proposed method would be used to preoperatively register the MRI image space with the physical catheter space. In the proposed scheme, the registration is performed with the help of a registration frame, which has a set of embedded electromagnetic coils designed to actively create MRI image artifacts. These coils are detected in the MRI scanner's coordinate system by background subtraction. The detected coil locations in each slice are weighted by the artifact size and then registered to known ground truth coil locations in the catheter's coordinate system via least-squares fitting. The proposed approach is validated by using a set of target coils placed withing the workspace, employing multi-planar capabilities of the MRI scanner. The average registration and validation errors are respectively computed as 1.97 mm and 2.49 mm. The multi-slice approach is also compared to the single-slice method and shown to improve registration and validation by respectively 0.45 mm and 0.66 mm.