Large Coil Research Articles

A heuristic algorithm to improving the coil slitting process in the steel industry

Abstract The steel industry is constantly facing problems and challenges that require optimisation to improve the production process. We present an algorithm to address a major challenge, the slitting problem, for a specific Spanish company. This problem arises when large steel coils need to be cut into smaller strips. Given the highly heterogeneous stock (coils come from previous operations), selecting the most suitable coils and defining the cutting patterns become very complicated due to operational and customer constraints. The company aims to reduce the leftovers and increase the service level (the difference between the weight requested by the customer and the weight supplied). The algorithm is currently in production and was validated using the company’s data and compared with an exact model. Results significantly improved the company’s operations, achieving a 50% reduction in leftovers and a much better service level in minutes, as opposed to the hours the company previously required. Although there are Mixed Integer Linear Optimization models that provide an optimal solution in small cases, they are not a viable alternative for the company because they require excessive computational time (even, in some cases, to obtain feasible solutions) and use overly expensive commercial solvers.

Single-phase flow heat transfer characteristics in helical coils with large coil diameters

Single-phase flow heat transfer characteristics in helical coils with large coil diameters

Impact of interference fringe visibility changes on closed-loop IFOGs operating across multiple fringes

This study investigates the impact of interference fringe visibility changes on closed-loop interferometric fiber optic gyroscopes (IFOGs) operating across multiple fringes. We introduce a model that addresses the challenges posed by spectral asymmetry and limited temporal coherence, which can induce scale factor non-linearity. By analyzing high-order fringes and employing suitable experimental setups with large fiber coil geometries, we demonstrate the effectiveness of our compensation model. Experimental results indicate significant reductions in scale factor non-linearity, with improvements of up to 9.3 times in one setup. This work highlights the importance of considering fringe visibility changes to enhance the dynamic range of IFOGs while ensuring measurement accuracy.

Initial results of the Hyperion IIDPET insert for simultaneous PET-MRI applied to atherosclerotic plaque imaging in New-Zealand white rabbits.

In preclinical research, in vivo imaging of mice and rats is more
common than any other animal species, since their physiopathology is very well-
known and many genetically altered disease models exist. Animal studies based on
small rodents are usually performed using dedicated preclinical imaging systems
with high spatial resolution. For studies that require animal models such as mini-
pigs or New-Zealand White (NZW) rabbits, imaging systems with larger bore
sizes are required. In case of hybrid imaging using Positron Emission Tomography
(PET) and Magnetic Resonance Imaging (MRI), clinical systems have to be used,
as these animal models do not typically fi t in preclinical simultaneous PET-MRI
scanners.
Approach. In this paper, we present initial imaging results obtained with the
Hyperion IID PET insert which can accommodate NZW rabbits when combined
with a large volume MRI RF coil. First, we developed a rabbit-sized image
quality phantom of comparable size to a NZW rabbit in order to evaluate the
PET imaging performance of the insert under high count rates. For this phantom,
radioactive spheres with inner diameters between 3.95 and 7.86 mm were visible
in a warm background with a tracer activity ratio of 4.1 to 1 and with a total
18-F activity in the phantom of 58MBq at measurement start. Second, we performed
simultaneous PET-MR imaging of atherosclerotic plaques in a rabbit in vivo using
a single injection containing 18-F-FDG for detection of infl ammatory activity,
and Gd-ESMA for visualization of the aortic vessel wall and plaques with MRI.
Main results. The fused PET-MR images reveal 18-F-FDG uptake within an
active plaques with plaque thicknesses in the sub-millimeter range. Histology
showed colocalization of 18-F-FDG uptake with macrophages in the aortic vessel wall lesions. 
Significance. Our initial results demonstrate that this PET insert
is a promising system for simultaneous high-resolution PET-MR atherosclerotic
plaque imaging studies in NZW rabbits.

A novel flexural damping channel magnetorheological damper with high effective magnetic field coverage and experimental verification of damping performance

Abstract Conventional magnetorheological dampers (MRDs) have limitations owing to their low effective magnetic field coverage, and improving MRD structures is a common approach to address this issue. However, many existing MRD designs have limitations such as large radial dimensions and high coil power consumption. Therefore, this paper transformed the conventional damping channel into the flexural damping channel to increase the effective magnetic field coverage of the MRD based on the conventionalstructure. And then, the pressure drop model was utilized to preliminarily determine the structural parameters of the new MRD. Subsequently, a multi-physics coupling finite element method (FEM) analysis model was constructed to accurately determine the structural parameters, ensuring that the novel flexural damping channel (NFDC) MRD increases the output peak damping force while reducing the radial dimension and input power. Furthermore, the damping force variable range is stabilized when the excitation current is zero (field-off). Finally, a large number of vibration tests were conducted on both the conventional and NFDC MRDs, and it was found that the NFDC MRD has better vibration energy dissipation capacity and higher output peak damping force while maintaining a basically same field-off damping force variable range compared with the conventional MRD. The above process not only proved that the NFDC MRD possesses excellent output damping capability and working condition adaptability, but also validated the operational effectiveness of employing the multi-physics coupling analysis method to design the NFDC MRD.

Optimal design of thick-walled circular coils for uniform magnetic field generation

Abstract Uniform magnetic field coils are widely used as electromagnetic equipment in industrial, medical, and research applications, with Helmholtz coils being a common configuration. For applications requiring a relatively high magnetic field (∼mT), Helmholtz coils typically feature a large coil cross-section. However, this characteristic makes them unsuitable for describing the magnetic field generated by a current loop model during the design process. In this work, we model the magnetic field of a large cross-section Helmholtz coil system, often referred to as a thick-walled Helmholtz coil. By employing a genetic algorithm, we transform the design problem of a Helmholtz coil into a constrained optimization problem. Subsequently, we propose a method for reverse designing a Helmholtz coil based on constraints on the target magnetic field. Finite element simulations verify the accuracy of the established magnetic field calculation model in describing the magnetic field generated by the thick-walled Helmholtz coil. Moreover, the designed Helmholtz coil effectively meets the design constraints and objectives. This method addresses the issue of significant errors in calculating the magnetic field and its uniformity resulting from the cross-sectional effect during the design of thick-walled Helmholtz coils. Furthermore, it satisfies the constraints for coil operating time and lightweight design.

How conductivity boundaries influence the electric field induced by transcranial magnetic stimulation in in vitro experiments

Although transcranial magnetic stimulation (TMS) has become a valuable method for non-invasive brain stimulation, the cellular basis of TMS activation of neurons is still not fully understood. In vitro preparations have been used to understand the biophysical mechanisms of TMS, but in many cases these studies have encountered substantial difficulties in activating neurons. The hypothesis of this work is that conductivity boundaries can have large effects on the electric field in commonly used in vitro preparations. Our goal was to analyze the resulting difficulties in in vitro TMS using a simulation study, using a charge-based boundary element model. We decomposed the total electric field into the sum of the primary electric field, which only depends on coil geometry and current, and the secondary electric field arising from conductivity boundaries, which strongly depends on tissue and chamber geometry. We investigated the effect of the conductivity boundaries on the electric field strength for a variety of in vitro experimental settings to determine the sources of difficulty. We showed that conductivity boundaries can have large effects on the electric field in in vitro preparations. Depending on the geometry of the air-saline and the saline-tissue interfaces, the secondary electric field can significantly enhance, or attenuate the primary electric field, resulting in a much stronger or weaker total electric field inside the tissue; we showed this using a realistic preparation. Submerged chambers are generally much more efficient than interface chambers since the secondary field due to the thin film of saline covering the tissue in the interface chamber opposes the primary field and significantly reduces the total field in the tissue placed in the interface chamber. The relative dimensions of the chamber and the TMS coil critically determine the total field; the popular setup with a large coil and a small chamber is particularly sub-optimal because the secondary field due to the air-chamber boundary opposes the primary field, thereby attenuating the total field. The form factor (length vs width) of the tissue in the direction of the induced field can be important since a relatively narrow tissue enhances the total field at the saline-tissue boundary. Overall, we found that the total electric field in the tissue is higher in submerged chambers, higher if the chamber size is larger than the coil and if the shorter tissue dimension is in the direction of the electric field. Decomposing the total field into the primary and secondary fields is useful for designing in vitro experiments and interpreting the results.

A Protection Method for Large HTS Coil by Copper Plate in Conduction Cooling System

A Protection Method for Large HTS Coil by Copper Plate in Conduction Cooling System

Characterization of a novel TORT cable wound of stabilized striated REBCO tapes for reduced magnetization AC losses

REBCO (rare-earth barium copper oxide) high-temperature superconducting tapes, have a high potential for winding of large magnet coils. Tapes on round tube (TORT) cables represent a promising option for achieving a conductor suitable for the winding of magnet coils. However, certain applications, such as accelerator magnets, require the use of superconducting cables with low magnetization alternative current (AC) losses. There are several methods to reduce AC losses in TORT cables. Our first approach was to get rid of eddy currents by replacing the copper former with dielectric materials based on polymers and composites, i.e. polyethylene terephthalate glycol-modified reinforced with carbon fibers. Additional reduction of hysteretic loss was achieved by striating of copper coated REBCO tapes. We employed chemo-mechanical striating, for these objectives. However, the superconductor is exposed during the striating process, which may lead to later moisture-related degradation. Hence multilayers based on Ti/AlN were deposited using magnetron sputtering in order to protect the superconductor immediately after the striating process from water and atmospheric moisture corrosion. Subsequently, striated tapes as well as the non-striated tapes were then wound onto formers with diameters of 10 mm, 7 mm and 5.5 mm, and then on the short TORT cables bending tests were performed. After each technological step, direct current measurements were performed on the samples and finally the AC losses were measured.

Fracture Toughness, Radiation Hardness, and Processibility of Polymers for Superconducting Magnets.

High fracture toughness at cryogenic temperature and radiation hardness can be conflicting requirements for the resins for the impregnation of superconducting magnet coils. The fracture toughness of different epoxy-resin systems at room temperature (RT) and at 77 K was measured, and their toughness was compared with that determined for a polyurethane, polycarbonate (PC) and poly(methyl methacrylate) (PMMA). Among the epoxy resins tested in this study, the MY750 system has the highest 77 K fracture toughness of KIC = 4.6 MPa√m, which is comparable to the KIC of PMMA, which also exhibits linear elastic behaviour and unstable crack propagation. The polyurethane system tested has a much higher 77 K toughness than the epoxy resins, approaching the toughness of PC, which is known as one of the toughest polymer materials. CTD101K is the least performing in terms of fracture toughness. Despite this, it is used for the impregnation of large Nb3Sn coils for its good processing capabilities and relatively high radiation resistance. In this study, the fracture toughness of CTD101K was improved by adding the polyglycol flexibiliser Araldite DY040 as a fourth component. The different epoxy-resin systems were exposed to proton and gamma doses up to 38 MGy, and it was found that adding the DY040 flexibiliser to the CTD101K system did not significantly change the irradiation-induced ageing behaviour. The viscosity evolution of the uncured resin mix is not significantly changed when adding the DY040 flexibiliser, and at the processing temperature of 60 °C, the viscosity remains below 200 cP for more than 24 h. Therefore, the new resin referred to as POLAB Mix is now used for the impregnation of superconducting magnet coils.

Evaluation of the Inductive Coupling between Coplanar Concentric Coils in the Presence of the Ground

An analytical approach is presented that allows deriving an exact series-form representation for the flux linkage between two physically large concentric circular coils located on a lossy soil. The expression comes from a three-step analytical procedure. First, the integral expression for the flux linkage is converted into a double integral consisting of a finite and a semi-infinite integral. Next, the semi-infinite integral is recognized to be a well-known tabulated Sommerfeld integral, which may be analytically evaluated straightforwardly. Finally, applying Lommel’s expansion allows rewriting the remaining finite integral as a sum of elementary integrals amenable to analytical evaluation. As a result, the flux linkage between the two coils is given as a sum of spherical Hankel functions of the wavenumber in the air and in the ground, multiplied by a coefficient depending on the geometrical dimensions of the coils. The accuracy and robustness of the proposed formulation is tested by comparing its outcomes with those generated by numerical integration of the complete integral representation for the flux linkage and with the results provided by previous analytical approaches to the same problem. It is found that the use of the derived expression for the inductance makes it possible to obtain significant time savings as compared to numerical quadrature schemes.

Low noise magnetic field compensation based on differential biplanar coils with small coil constant

Magnetic field noise is a key factor limiting the resolution of quantum precise measurement. In active magnetic field compensation systems, the large coil constant and fixed noise of the coil and current source, respectively, cause excessive noise. This study proposes a differential biplanar coils (DBCs) design method by comprehensively optimizing two sets of biplanar coils with differential evolution (DE) algorithm, which can reduce the coil constant by two magnitude orders while ensuring high uniformity. The peak-to-peak magnetic field at the center point is reduced to 0.8 pT, and the magnetic field noise is reduced to 8 fT/Hz, which is a reduction of 94.4%. The low noise active magnetic compensation system based on the differential biplanar coils can improve the accuracy of the magnetic shielding room (MSR) internal magnetic field control and reduce magnetic field noise effectively. The proposed method contributes to generating a near-zero magnetic field environment with low magnetic field noise, which is critical to promoting magnetoencephalography (MEG) measurements.

Design of High Transmission Frequency Circuit for Multiturn Small Loop Transient Electromagnetic Detection

Limited by urban road width and other factors, urban TEM detection can only use multiturn small loop as the transmitting coil. The traditional TEM transmitting circuit cannot transmit high frequency repetitive pulse for such large inductance coil. In order to solve this problem, a high transmission frequency circuit is proposed and built in this paper, which can clamp both the rising and falling edges of the emission current, and effectively improve the frequency. The repeated transmission frequency of 250 Hz for 0.73 mH coil at current of 30 A is realized. The circuit effectively improves the strong magnetic field excitation ability, which is of positive significance for the application of multiturn small loop TEM in urban environment.

Influence of a high magnetic field to the design of EU DEMO

The limitation considered in the definition of DEMO in 2016 to not exceed the magnetic field strength foreseen in the ITER machine is reviewed here. At the time, a Nb3Sn superconductor operated in a magnetic field, Bmax, no greater than 13 T was considered to rely on existing and mature technology. This limitation is no longer seen as a boundary here, recognizing that the first model coil with Rare Earth Yttrium Barium Copper Oxid (REBCO) superconductor was recently operated at a field of >20 T.DEMO must have a burning plasma which, at a higher magnetic field, is reached in a significantly smaller plasma volume. Accordingly, a system code study was carried out to size the DEMO machine by varying the magnetic field. The outcome confirmed previous observations that the magnetic field strength is linearly dependent on the plasma aspect ratio, A, when we target a minimum machine size. It was notable that in a machine with a high A, the increased Bmax raises the plasma performance but does not allow for reducing its size. The reduced plasma elongation of plasmas with high aspect ratio is a caveat as it reduces the gain in plasma performance achieved in the high field. Furthermore, the higher magnetic field at high A challenges the engineering of the magnets and associated structures, and substantially increases the heat loads on the divertor. This article assesses the engineering feasibility assessment of large DEMO coils operated at high field, also considering advanced i.e., non-ITER like, mechanical concepts. No advanced coil concepts appeared suitable for a large device like DEMO. Consequently, DEMO design points with lower Bmax and lower A were investigated. This resulted in the identification of a maximum magnetic field of approximately 11–12 T to ensure the engineering feasibility of the DEMO TF coils.

Fluctuation of Magnetic Field in Magnetic Nano-Particles Thermometer

In this study, some important factors have been identified for the fluctuation of the magnetic field over time, which provides a basis for improving the temperature measurement accuracy and long-term stability of the magnetic nanoparticles thermometer (MNPT). We improved the mathematical model between the relative error of the magnetic induction intensity and the temperature measurement error of MNPT. The simulation founded that when the relative error of the magnetic induction intensity is kept within the range of <0.01%, the temperature measurement error is less than 0.1 K. Then, the multi-physics (magnetic field, temperature field, and thermal stress field) coupling relationship in the Helmholtz coil is established. During the coupling process, the temperature field of the Helmholtz coil affects the resistance of coil wire, and its thermal stress field is affected by the temperature field, which also changes the coil radius. After the temperature field and thermal stress field change, the magnetic field fluctuates immediately. Further simulation found that the problem of coil temperature rise becomes more serious as the size of the Helmholtz coil increases. The method of forced air cooling can make the fluctuation of the large Helmholtz coil magnetic field < 0.01%, and improve the measurement accuracy of MNPT.

Automated surface defect detection in forged parts by inductively excited thermography and magnetic particle inspection

ABSTRACT Inductively excited thermography has been shown to detect cracks in metallic components with good sensitivity. It is discussed as an alternative to magnetic particle testing. An open question to achieve acceptance in the industry is its testing reliability. A study with in total 200 forged steel parts was performed in order to compare the testing reliability of automated inductively thermographic testing and magnetic particle inspection. A robot supported thermographic inspection station was used. An inductor with orientation-independent crack detection was built up and tested. The thermographic phase images obtained were analysed by an automatic defect detection procedure based on machine learning techniques. Results of magnetic particle inspection served as a reference. Depending on the type of test object, an agreement of 68% to 82% was achieved, if only large indications of thermography were considered. The weak thermographic indications turned out to be due to shallow cracks (<150 µm depth). Improvement of the testing speed can be achieved by inspection inside large coils.

An integrated spiral DGS and an open stub meander-line resonator in the 0.13-µm BiCMOS technology for a 18-GHz band oscillator

In this paper, an 18 GHz voltage-controlled oscillator (VCO) with improved phase noise (PN) and smaller size is proposed. The filter consists of an open stub resonator and an integrated spiral Defective Ground Structure (DGS) resonator. The proposed oscillator is designed in the 0.13-µm SiGe BiCMOS technology. The differential cross-coupled VCO uses a bandpass filter. In this work, the conventional large-size coil is replaced by a resonator based on our proposed open stub resonator and defected ground structure (DGS) where the filter is equivalent to the large coil and the associated capacitors. The use of the filter results in a great reduction of VCO size, low losses, and low power consumption, hence an enhancement in the quality factor. The integrated spiral DGS is etched on the third metal layer (M3) below an open stub meander line onthe top metal layer (TM2) of the 0.13-µm top metal two (TM2) BiCMOS technology. The proposed VCO has a small die area of 0.089 mm2 and has FoMA of 188.8 dB and a power consumption is 13.38 mw. The simulated carrier frequency and phase noise are 18-GHz and −123.59 dBc/Hz (−103.7 dBc/Hz) at 10-MHz (1 MHz) offset frequency, respectively, which results in a figure of merit of 177.37 dB.

Open-Source Magnetometer for Characterizing Magnetic Fields in Ultracold Experiments

We demonstrate a fully automated open-source magnetometer designed primarily for characterization of magnetic fields produced by coils, permanent magnets or by parasitic sources. It is based on an Arduino Mega microcontroller and a three-axis Hall sensor with a measurement range of ±8 G per axis and the RMS of the field readout below 0.3 mG. For all practical purposes, the sensor displacement during data acquisition is virtually unlimited, which can be particularly useful for characterizing large or extended coils like Helmholtz cages or Zeeman slowers. All components needed for the construction are cheap and widely available off-the-shelf elements or are 3D-printed. The operation of the magnetometer is controlled via a graphical user interface (GUI), which manages all essential functionalities, like data acquisition and plotting. The GUI also incorporates additional features, like data averaging, calibration of the displacement of the Hall sensor or real-time readout of the magnetic field, useful for monitoring magnetic field changes. We have used a pair of rectangular coils constructed for a potassium–cesium 2D magneto-optical trap to benchmark the performance of the magnetometer. We have obtained good agreement with both simulations and measurements acquired with a commercial gaussmeter.

Study on the State Prediction of a Pool-Cooled Large Superconducting Coil Using Machine Learning

For the LHD subcooling system composed of pool-cooled large superconducting coils wound with NbTi superconductors, a machine learning technique was introduced to increase the reliability of the system. The machine learning model for the state prediction of the system was developed using the technique, together with the data accumulated in the LHD plasma experimental campaign. Regarding the temperature changes in the system due to coil excitation and discharging, it is possible to make predictions using the model. Especially for the usual coil current waveform in a helical coil operation, which is a trapezoidal waveform, the model achieved high prediction accuracy.

Performances of the First Full-Length Module Prototype of the MgB$_\text{2}$ Round Coil Superferric Magnet at LASA

Developed within the INFN LASA and CERN collaboration agreement for the construction of the High Order Corrector Magnets for the High Luminosity-LHC project, the first half section of the Round Coil Superferric Magnet proved the feasibility of a new compact and modular corrector magnet type using MgB <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> superconductor. Different from the classic superferric layout, its unconventional design exploits the iron permeability to shape, with an arbitrary number of poles, the solenoidal field created by a large bending radius coil suitable for strain-sensitive superconductors. After the design upgrade of the winding and impregnation process, in this paper, we describe the realization of the second superconducting coil for the full module length prototype of the sextupole corrector. The integration of the two half-sections of the magnet module is analyzed in detail and the performances of the newer one, during tests at cryogenic temperature, are compared with the older results. Finally, the powering test of the full module and its magnetic field characterization are described and compared with the electromagnetic simulations and expected performances.