Coil Displacement Research Articles

TF Coil Displacement Distortion FE Analysis Simulating Non-Constant Assembly Gap Between Wedging Interfaces of TF Coils

TF Coil Displacement Distortion FE Analysis Simulating Non-Constant Assembly Gap Between Wedging Interfaces of TF Coils

Spring coil displacement after interventional embolization of severe pelvic fracture: a case report.

Haemorrhagic shock, which arises as a complication of pelvic fracture subsequent to severe trauma, represents a perilous state. The utilization of interventional endovascular haemostasis assumes a pivotal role in the management of patients with vascular injury following pelvic fracture. This article reports the treatment of a patient with pelvic fracture caused by a serious work-related vehicle accident. Despite the implementation of timely blood and fluid transfusion to combat shock, the application of aortic balloon obstruction, and interventional iliac artery embolization for haemostasis, the patient's condition failed to display any discernible improvement. Repeat angiography further revealed a displacement of the interventional embolization material, and the patient subsequently died of multiple organ failure. The occurrence of spring coil displacement is infrequent, but the consequences thereof are considered grave, necessitating meticulous discernment in the selection of haemostatic materials for this type of patient. The diagnostic and therapeutic processes encompassing the particular case described here were analysed and are discussed with the objective of augmenting the efficacy and success rate of treatment modalities for patients in similar circumstances.

Analyzing the Nonlinear Performance of Miniature Loudspeakers in Consideration of the Creep Effect

Miniature loudspeakers exhibit pronounced nonlinear characteristics due to physical size limitations and the demand for sufficient sound pressure. The primary nonlinear properties, including the force factor, mechanical stiffness, and mechanical resistance, depend on the displacement or velocity of the voice coil. The creep effect in the loudspeaker’s suspension system, which significantly affects low-frequency displacement, is often neglected in existing studies on nonlinear dynamics. This study enhances the modeling of miniature loudspeakers by incorporating the creep effect into an extended nonlinear model. The voice coil displacement and total harmonic distortion (THD) predicted by the extended model were validated against experimental data. The displacement and THD values predicted by the nonlinear model in consideration of the creep effect corresponded closely to the actual measurement values, substantiating the effectiveness and precision of the model.

Uncertainty Quantification of Human Electromagnetic Exposure From Electric Vehicle Wireless Power Transfer System

With the rapid development of electric vehicles (EVs), the wireless power transfer (WPT) technology of EV is becoming more and more mature. The safety of human electromagnetic exposure caused by the WPT system of EV has become the focus of research. Considering the practical application of EV WPT system, this paper studies the electromagnetic exposure of human body based on the uncertainty quantification theory. A sparse polynomial chaos expansion method is used to establish the surrogate model of the mean value of some human organs’ SAR, and the probability distribution function of SAR is calculated. The Sobol is used to quantify the impact of relevant variables on SAR. The final calculation results show that when the person is on the side of the EV, the offset between the magnetic coupling coils of the WPT and the lateral displacement of the human body on the side of the EV have a greater impact; When a person is at the rear of the EV, the vertical displacement of the magnetic coupling coils of the WPT has a greater impact on the longitudinal displacement of the human body at the rear of the vehicle. Combined with the above analysis, this paper can provide reasonable suggestions for the safety protection of electromagnetic exposure of human body in the WPT of EVs.

Inductance and Electrodynamic Forces in Circular Turns with Parallel Axes

With a wireless method of transmitting electrical energy to autonomous objects, a need may arise to use connecting devices with inductively coupled structural elements. When choosing such devices, their effectiveness should be evaluated taking into account the technological and design features of the embodiment. Expressions for mutual inductance and electrodynamic forces with parallel displacement of mating turns and disk coils are considered. Simplified expressions for the derivative of the inductance coefficients in the coordinate characterizing the parallel displacement of the loops are obtained. By using the obtained expressions, the effect of parallel displacement of the loops on the electrodynamic interaction forces can be evaluated. The obtained expressions are verified by numerically comparing them with the exact solution. On this basis, the maximum level of convergence of the results has been determined.

CT-guided placement of microcoil end in the pleural cavity for video-assisted thoracic surgical resection of ground-glass opacity: a retrospective study

BackgroundThe aim of the study was to investigate and summarize the effectiveness and safety of CT-guided microcoil localization before video-assisted thoracic surgery (VATS) for the removal of ground-glass opacity (GGO).MethodsA total of 147 patients with GGO who were treated at our hospital between January 2019 and February 2021 were retrospectively analyzed. They were divided into two groups according to the final position at the end of the microcoil: intracavity (n = 78) and extracavity (n = 69), which were compared based on puncture complications and influence of the coil end position on VATS.ResultsThe proportions of supine and prone positions in the intracavity group were significantly higher than those in the extracavity group (82.1% vs. 66.7%, P < 0.05). The incidence of intrapulmonary hemorrhage, chest pain, and coil displacement in the intracavity group was significantly lower than that in the extracavity group (28.2% vs. 46.4%, 19.2% vs. 39.1%, 1.3% vs. 11.6%, P < 0.05, respectively); however, the incidence of pneumothorax was not significantly different (P > 0.05). The time of VATS and the rate of conversion to thoracotomy in the intracavity group were significantly lower than those in the extracavity group (103.4 ± 21.0 min vs. 112.2 ± 17.3 min, 0% vs. 5.8%, P < 0.05, respectively).ConclusionCT-guided placement of the microcoil is a practical, simple, and convenient localization method before VATS, with a high success rate and few complications. Furthermore, it is a better alternative method to place the end of the coil in the pleural cavity because of the lower complication rate, shorter VATS time, and lower rate of thoracotomy conversion.

Effect of inductor types and shapes on the characteristics of an inorganic EL driven by wireless power transfer

A wireless power transfer (WPT) circuit was developed for an inorganic electro-luminescent (EL) device. When transmission and receiver circuits are both in resonant mode, low operating voltage of 30 V was enough to achieve the EL luminance as high as 180 cd m−2. As for the transmission and the receiver coils, different types and shapes are studied to clarify those effects on the EL luminance and transmission efficiency. Solenoid coils generally presented higher luminance than other types. Polygonal solenoid coils resulted in even higher luminance and transmission efficiency than circular solenoids. A spiral or a spider coil, in which air core area is much smaller than the solenoid coil, was found to be less sensitive to coil displacement. The difference in EL performances with the variation of coils suggests the possibility of further improvement the WPT system.

Lung nodule localization in hybrid room before minimally invasive thoracic surgery: series of 20 cases and literature review.

ABSTRACTObjective To describe an experience in the preoperative localization of small pulmonary nodules and ground-glass lesions to guide minimally invasive thoracic surgery; in addition, a literature review was conducted, including the main advantages and disadvantages of the different agents used, and site marking in a hybrid operating room.Methods A retrospective search was conducted in a Interventional Radiology Department database, between March 2015 and May 2019, to identify patients undergoing preoperative percutaneous marking of lung injuries measuring up to 25mm.Results A total of 20 patients were included and submitted to descriptive analysis. All patients were marked in a hybrid room, at the same surgical-anesthetic time. Most often used markers were guidewire, Lipiodol® and microcoils. Despite one case of coil displacement, two cases of pneumothorax, and one case of hypotension after marking, all lesions were identified and resected accordingly from all patients.Conclusion Preoperative percutaneous localization of lung injuries in hybrid room is an effective and a safe technique, which can have decisive impact on surgical resection. The choice of marker and of the operating room scenario should be based on availability and experience of service. Multidisciplinary discussions with surgical teams, pathologists, and interventional radiologists are crucial to improve outcome of patients.

A Pulsed Current Inductive Method and Its Applications for Continuous Measurement of the Critical Current of Long Superconducting Tapes

Recent progress in high-temperature superconducting (HTS) applications, especially the success of compact Tokamak magnets, has brought great opportunity for HTS coated conductors (CCs). The present methods for measuring the critical current of CCs, including both dc transport measurements and inductive measurements, cannot fully satisfy the requirements of material manufacturers. We have formerly proposed a pulsed current inductive (PCI) method to solve this issue, which is different from the traditional pulsed current measurement since no voltage contact is required. The signal voltage is picked up by a coil placed near the sample. The other difference is that the PCI method utilizes one ramping pulse instead of a series of flat-top pulses. The PCI method does not suffer from inductive voltage interference. It is also fast due to the one pulse feature. The heat generation during the test is even smaller than that in the normal pulsed method. The PCI method is a fast, data-robust, and sample-safe transport measurement. In this article, the influences of the test conditions, including the coil displacement, coil shape, fluctuation of the tape <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n$ </tex-math></inline-formula> value, and tape width, were analyzed, where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n$ </tex-math></inline-formula> refers to the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$E$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$J$ </tex-math></inline-formula> power law exponent of the superconducting tape. An apparatus for reel-to-reel critical current measurement of HTS tapes was constructed based on the PCI method. An 11-m tape was tested with a relatively high resolution of 18.5 mm and a speed of 0.3 m/min, which can be upgraded with multiple sensors. The combined uncertainty of the method was estimated to be 4% + 5 A. Short sample experiments showed that the relative deviation of the PCI method from the dc transport method was mostly less than 5%, without the introduction of any fitting parameters. A good step toward real application of the PCI method has been achieved in this work. The need to systematically study the influence of sample inhomogeneity in the future is also shown.

Acoustic Control through Gradient Coil Design Using a Finite-Difference-Based Method for MRI

An acoustic control scheme is proposed in this paper through the process of gradient coil design for magnetic resonance imaging (MRI). With a finite-difference-based method, the stream function and coil displacement caused by fast gradient switching can be unified by a simplified momentum equation, which can be incorporated into the conventional gradient coil design. A three-dimensional transverse gradient coil with an edge-connected cylindrical structure is used as a design example to verify the proposed design method. In addition, an acoustic model is established to simulate the sound pressure level (SPL).In the model, two hemispherical air volumes are added flush with the ends of the cylindrical main magnet to mimic the free propagation of sound waves on the boundaries. The simulation results show that by optimizing coil displacement, the overall SPL can be attenuated by 4 dB over the frequency range from 0 to 3000 Hz with the displacement reduced by about 50%, at the cost of a figure of merit (FOM) loss by about 8%. Therefore, the proposed acoustic control scheme can be used as a complement to conventional acoustic control methods for further noise reduction.

Efficacy of endovascular treatment of distal aortic dissection involving abdominal visceral segment with bare-metal stents related technique

Objective: To investigate the effect of bare-metal stent related technique on distal aortic dissection involving abdominal visceral segment. Methods: A retrospective analysis was performed on clinical data of 33 patients with distal aortic dissection involved abdominal visceral segment, who hospitalized in the Vascular Surgery Department of Shanghai Changhai Hospital from July 2012 to September 2019. The effect of the treatment was evaluated according to the clinical and preoperative, intraoperative and follow-up imaging data derived from (aorta computed tomography angiography (CTA) and digital subtraction angiography (DSA)) as well as the changes of the maximal diameter of the aorta and the thrombosis of the false lumen of the dissection. The criteria were as follows: the maximum diameter change of aortic dissection<5 mm was defined as stable; the maximum diameter decrease of aortic dissection≥5 mm was defined as effective reduction; the maximum diameter increase of aortic dissection≥5 mm was defined as expansion; the definition of diameter change of false lumen was the same as above. The hospital complications, clinical symptoms and survival were recorded. Results: There were 28 male patients in this cohort, the mean age was (57.6±4.9) years old. Twenty-one patients were treated with bare-metal stent and coils technique, of which 8 patients were jointly treated with stent grafts. Twelve patients were treated with multi-layer bare-metal stent technique, of which 4 patients were jointly treated with stent grafts. Intraoperative DSA image results showed that the visceral arteries were patent during the treatment, and the blood flow velocity of the false lumen was reduced in all 33 patients. There were no adverse events such as distal outflow tract embolism and coil displacement during the operation. During the period of hospitalization, one patient developed intimal rupture of subrenal abdominal aortic dissection on the fourth day after operation and emergency endovascular graft exclusion was performed for abdominal aortic dissection, and the patient recovered well from the emergency operation. The follow-up time was (16.7±14.0) months. One patient died 1 year after surgery due to non-disease-related factors. Follow-up CTA imaging results showed that the maximum diameter of the aorta in abdominal visceral segment tended to be smaller ((39.1±13.4) mm vs. (41.3±11.9) mm, P=0.469), and the maximum diameter of the false lumen was significantly reduced ((16.2±12.9) mm vs. (23.5±10.7) mm, P=0.014). The maximum diameter of the aortic dissection was reduced in 12 cases, stable in 19 cases, expanded in 2 cases. The maximum diameter of the false lumen was effectively reduced in 22 cases, stable in 10 cases, and expanded in 1 case. Four patients developed small endoleak in the false lumen, one of them was nearby the renal artery stent, and the remaining patients experienced complete thrombosis of the false lumen. Conclusions: Endovascular treatment of distal aortic dissection involving abdominal visceral segment with bare-metal stents related technique could promote the shrink and the thrombosis of the false lumen, and slow down the blood flow from the tear into the false lumen in the setting of patency of visceral arteries.

3D Mechanical Analysis of a Compact ${\text{Nb}}_{\text{3}}{\text{Sn}}$ IR Quadrupole for EIC

The Electron Ion Collider (EIC) will require large aperture quadrupole magnets for the Hadron beam in the insertion region. Key requirements include high field, compact size, and tight control of the fringe fields. A 120 mm aperture, 308.4 mm outer diameter actively shielded <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\rm {Nb}}_{3}{\rm {Sn}}$</tex-math></inline-formula> quadrupole model is under development to support these goals. This work is being carried out by a collaboration of BNL, JLAB and LBNL. A compact shell-based structure preloaded with a bladder and key system was developed for this project. In this paper, the effect of the compact structure on the mechanical behavior was investigated. In particular, the impact of the assembly tolerances and coil size variations on the actual coil stresses and bladder pressures was computed and compared with results from larger bladder and key structures developed for the LHC IR. The longitudinal preload is provided by stainless steel rods. Differently from other bladder and key magnets, the rods are first preloaded axially before coil axial load is applied. This new design aims to increase the overall stiffness of the system and reduce the longitudinal coil displacement during powering. Based on the results of a 3D mechanical analysis, the preliminary pre-load targets for the EIC quadrupole assembly will be reviewed and discussed.

Efficiency Enhancement in a Multi-coil Wireless Power Transfer System

Wireless power transfer technology via magnetic resonance coupling now has significant interest in industry and research with many applications. This paper proposes a linear multiple transmitter coil array (5 coils) for wireless power transfer for added gain and hence higher transfer efficiency in comparison to a single transmitter coil. The frequency splitting effect as a result of the coupling between the resonant transmitter coils due to their close proximity is shown to reduce the transfer efficiency to a receiver. The effect of the array spacing on splitting effect suppression is verified. It is shown that the splitting effect is sup-pressed as the distance between the coils is increased leading to a higher received signal and hence higher efficiency. Proposed horizontal displacement of the middle transmitter coils (2nd and 4th coils) in the coil array is shown to suppress frequency splitting. To further suppress the splitting effect due to the magnetic coupling between the transmitter coils, a multiple transmitter array is proposed with different coil turns. Thus it is shown that designing the multiple coil array with mixed number of coil turns (the 2nd and 4th coils are designed to have different number of turns as compared to the other three coils) causes uniform coupling among the coils reducing and eventually eliminating the splitting effect. Also to increase the efficiency at the receiver coil, displaced stacked coils are introduced on top of the coil array. The pro-posed stacked coil array is demonstrated to improve the transfer efficiency. Using the techniques, the proposed linear array structure achieves a transfer efficiency of 36.9% for a receiver coil at the boresight of the array at a transfer distance of 40 cm.

A New Interferometric System for the BIPM Kibble Balance

The article describes a new interferometric system for measuring the coil displacement in the BIPM Kibble balance. The system has led to a significant reduction in both the type A and type B uncertainty of the Kibble balance measurement. Compared to the previous version, the new instrument doubles the measurement signal thanks to a novel design. The optical and mechanical setup is more compact, more stable, and less sensitive to vibration noise. It is also more easily aligned, particularly for adjusting the interferometer beams vertically.

A study on the optimal design and the performance evaluation of electromagnetic energy harvesting device for the rolling stock application

An electromagnetic energy harvesting device was studied based on the design parameters of an energy harvesting device for the power source of wireless sensors node on the rolling stock. The characteristics of the generated power by the energy harvesting device were tested using the laboratory equipment and a rolling stock (a high-speed train). First, a cantilever beam energy harvesting device, which allows for easy adjustment of the length according to the frequency and the power according to the cantilever beam materials, was researched. In addition, the new design for a practical resonant energy harvesting device for the railroad system was performed. To realize the performance of the practical resonant energy harvesting device, the generated power characteristics of the energy harvesting device were tested according to the moving displacement, the number of coil turns, and the initial coil displacement between the coil and magnet. The evaluation of the performance of the manufactured resonant energy harvesting device for the railroad system, which the parameters were determined based on the test results, was conducted under real driving conditions in the high-speed train, which was traveling at 300 km/h. Finally, this study analyzed whether the power generated could be applied to the wireless sensor nodes for the railroad system.

A Brushless Dual-Electrical-Port Dual-Mechanical-Port Machine With Integrated Winding Configuration

The brushless dual-electrical-port dual-mechanical-port (BLDD) machine is a newly developed machine type which can replace conventional power split system based on planetary gear. BLDD machine always contains one stator and two coaxial rotors, and two sets of windings are required to control two rotors. In this article, a novel integrated winding configuration is proposed to replace two original windings with different pole number, i.e., the integrated winding should have the ability to produce two pole number, independent-control magnetomotive forces (MMFs). By carefully designing coil displacement and terminal configuration, two current components with different phases are skillfully injected to the integrated winding, which produces MMFs with different pole-pairs. Compared with original winding configuration, the proposed integrated winding has two main advantages. First, higher current can be injected under the same copper loss, which improves the torque density of BLDD machine indirectly; second, the configuration of the integrated winding is the same as one set of overlapping winding, which contains only one coil configuration and simplifies the manufacture process. In this article, the structure and operation principle of the integrated winding are detailedly introduced, and the electromagnetic performance of BLDD machine equipped with integrated winding is investigated by finite element analysis (FEA), finally a prototype is also manufactured and tested to verify the analysis.

CLINICAL AND RADIOLOGICAL EVALUATION OF PATIENTS WITH SUBARACHNOID HAEMORRHAGE SUBJECTED TO DIGITAL SUBTRACTION ANGIOGRAPHY IN AL-HUSSEIN NEURO-INTERVENTION UNIT

Background: Subarachnoid hemorrhage (SAH) refers to bleeding that occurs primarily within the subarachnoid space, in between cases of spontaneous SAH and rupture of an intracranial saccular aneurysm accounts for approximately 85%. Objectives: The aim of this study was to assess clinical presentation, risk factors and the etiology of subarachnoid hemorrhage in a sample of Egyptian patients, and also assess the outcome of endovascular management and complications. Patients and Methods: The study was carried out on patients with SAH who were subjected to endovascular neuro-intervention unit in AL-Hussein University Hospital, including patients with SAH retrospectively from 2006 to 2018, and the newly diagnosed patients during 2019. Results: During the period from May 2006 to May 2019, 560 patients with SAH has been admitted. 136 patients (24.2%) were excluded from the study as they were critically ill. Their Hunt and Hess score were 4 to 5. Also, another 51 has been excluded due to missed files or discharge against medical advice. The remaining 373 patients. 145 patients were angiographically free, Patients with aneurysm were 228 patients, 77 patients died before therapeutic endovascular treatment as they delayed due to financial troubles, The remaining patients were 151, The most common type of aneurysm between those patients was anterior communicating aneurysm (27.8%), then MCA aneurysm (17.8%), posterior communicating artery aneurysm (13.9%), para-ophthalmic artery aneurysm (6.6 %), basilar artery aneurysm (5.9%), posterior inferior cerebellar artery aneurysm (6.4%), supraclinoid carotid artery aneurysm (3.1%), peri callossal artery aneurysm (3.3%), T carotid artery aneurysm (7.2%), superior cerebellar artery aneurysm (1.9%), inferior cerebellar artery aneurysm (2.6%) and multiple aneurysms (6.6%). The complications of endovascular treatment in studied patients occurred in 13 patients (3.4%) in the form of aneurysmal rupture, coil displacement, hydrocephalus and vessel rupture. Conclusion: Cerebral catheter angiography is a safe, feasible and efficacious procedure. The new technique in the endovascular management of the cerebral aneurysm as balloon or stent assisted technique and flow diverter stent is greatly reducing the complication rate and making the outcome is very promising.

Cyclic Behavior of Wendelstein 7-X Magnet System During First Two Phases of Operation

The sophisticated large magnet system of the Wendelstein 7-X (W7-X) stellarator has been operated during first two experimental campaigns at the Max-Planck-Institute for Plasma Physics in Greifswald, Germany, for roughly 13 months. Its 70 superconducting coils (NbTi CCIC) are extraordinary not only due to complex 3D shapes of 50 non-planar coils, but also due to a non-linear support system. In addition, five big resistive coils with the aim to correct W7-X error fields are installed on the outer cryostat and use rubber pads in their supports to compensate thermal expansion of the coils. The structural behavior of the W7-X magnetic system is monitored and evaluated on the basis of the analysis of the signals from the extended set of mechanical and temperature sensors. Several cooldown/warming up and thousands of electromagnetic cycles with different loading patterns and with up to 70% design load magnitude have been performed by the system successfully. The focus of this paper is on the cyclic structural behavior of the W7-X magnet system and the comparison with finite element predictions. Several related issues such as bolts and rubber pads prestress degradation, support slippage development, evolution of mutual coil displacement, loading path dependence of stress levels, sliding weight support (cryoleg) adjustment, and sensor failure are addressed. Lessons learned so far are also briefly summarized.

Loudspeaker Analysis: A Radar Based Approach

Recently, radar based micro-Doppler signature analysis has been successfully applied in various sectors including defence, biomedical, and automotive. This article presents the novel use of radar micro-Doppler for loudspeaker analysis. The approach offers the potential benefits of characterizing the mechanical motion of a loudspeaker in order to identify defects and design issues. Compared with acoustic based approaches, the use of radar allows reliable measurements in an acoustically noisy end of a production line. In addition, when compared with a laser vibrometric approach, the use of radar micro-Doppler reduces the number of measurements required and provides direct access to the information of the metallic components of the loudspeaker. In the paper experimental results and analysis of the micro-Doppler signatures of loudspeakers using low cost radar systems are presented. Based on Thiele&Small parameters, the voice coil displacement is modelled and micro-Doppler signatures for a single tone and a sine sweep stimulus are presented. Furthermore, in order to characterize the speaker with a single radar measurement, a methodology to measure mechanical frequency response of loudspeakers is also shown.

Consideration of the Influence of Coil Misalignment on the Chinese First Quasi-Axisymmetric Stellarator Magnetic Configuration

The effects of misalignment of modular coils on various physical properties in the Chinese first quasi-axisymmetric Stellarator (CFQS) are discussed in this study. To estimate the effects quantitatively, simple assumptions are made regarding the structure of coil displacement. We consider the following three cases: displacement in radial direction (Case A), displacement in the vertical direction (Case B), and displacement by tilting (Case C). In all cases, we assume that the displacement structure has a stellarator symmetry. These assumptions are employed to calculate the change in the magnetic surfaces, rotational transform profile, magnetic well depth profile, and the effective helical ripple. Calculation results show that if the magnitude of displacement is less than 10 mm, the effects on these physical properties are small, and the good neoclassical transport property is retained.