Single-coil System Research Articles

Enhancing forming accuracy in aluminum alloy variable-diameter tubes through dual-coil controllable electromagnetic forming

High-accuracy forming of aluminum alloy variable-diameter tubes imposes strict requirements on force field design. Although electromagnetic forming has shown unique advantages in enhancing the formability of aluminum alloy materials, its shortcomings lie in the single and difficult-to-adjust force field, which limits its application in variable-diameter tubes. To address this challenge, a novel dual-coil electromagnetic forming approach with good controllability of force field is proposed. Numerical simulations and experiments are both conducted to showcase the superiority of this approach in forming variable-diameter aluminum alloy tubes. The results demonstrate that the forming accuracy of AA6061-O variable-diameter tubes has significantly improved compared to a traditional single-coil system, in which the maximum die-fitting gap is reduced from approximately 2 mm to less than 0.22 mm. Furthermore, it is identified the force field produced by the single-coil system causes a local cavity gap between the tube and the die, which adversely affects the forming accuracy. In contrast, the improved force field produced by the dual-coil system facilitates bottom-to-top deformation of the tube, thereby avoiding undesirable cavity gaps and achieving high forming accuracy. Importantly, the dual-coil forming system offers significant controllability of the Lorentz force field by adjusting the coil discharge, making it suitable for variable-diameter tubes of different sizes without changing the coil structure. This work represents a substantial advancement in controllable tube forming, offering a new approach to force field design and holding promise for extensive applications in the forming of variable-diameter tubes.

A Modified DDQ Track for Interoperable EV Dynamic Charging

The design and realization of dynamic EV charging systems face challenges such as large coupling variations and interoperability requirements. The study of the dynamic process using exhaustive simulation approaches is also time-consuming. This paper proposes a two-phase DDQ track topology focusing on improving interoperability and reducing power transfer fluctuations. A method to simplify the design process is also presented. By converting the dynamic procedure of a multi-coil system into a mathematical model of a single-coil to single-coil system, the method simplifies the evaluation of numerous designs into a calculation script associated with a much lower simulation count. Analysis and evaluations based on coupling profile, interoperability, and cost-effectiveness are carried out from both general and statistical points of view. A design that meets minimum misalignment requirements and has a stable coupling profile is selected for prototyping. The experiment at a 10-kW power level verifies the simulation and analysis.

Improving the uniformity and controllability of tube deformation via a three-coil forming system

The Lorentz force distribution on a tube is the dominant factor that determines the tube deformation behavior in the electromagnetic forming process. However, the existing forming technologies in this field are mainly based on a single-coil system, which results in a relatively fixed Lorentz force distribution and makes it difficult to control the forming process or the final tube shape. To solve this problem, a three-coil forming system composed of three sub-coils and two pulsed power supplies is developed for tube forming in this work. Both numerical simulation and experimental results show that the three-coil system can be easily applied to alter the Lorentz force distribution through adjusting the discharge voltage of sub-coils, providing an effective way to improve the deformation uniformity and control the deformation shape. It is found that an AA6061-O aluminum alloy tube with an inner diameter of 76 mm and a thickness of 2 mm can be deformed with a homogeneous deformation range of about 23.56 mm via the three-coil system in the experiments, while the range is only about 11.48 mm under the same conditions when using the conventional single-coil system. Meanwhile, it is demonstrated that the three-coil system can achieve a variety of tube shapes including concave and convex profiles with different uniformity. The developed method and obtained results are of good value for expanding the application of electromagnetic tube forming.

Design of Multi-Coil Wireless Power Transfer System for Gastrointestinal Capsule Robot

The existing wireless power transfer (WPT) systems for gastrointestinal capsule robot have the problems of small coupling coefficient and low power transmission efficiency (PTE). The reasons are due to the long distance between the transmitting coil and the receiving coil and the large difference in size. A new type of WPT system is designed, which uses three sets of small coil pairs to form a power supply unit (PSU), and utilizes multiple PSUs to form a multi-coil WPT system. Compared with single-coil system, the multi-coil system can achieve higher power utilization by switching between PSUs, instead of opening all PSUs. ANSYS Maxwell is used to perform finite element modeling on the PSU, analyzing the characteristics of the transmitting magnetic field. The results of the experiment show that when the distance between the small coil pairs in the PSU is 180 mm, the magnetic field has relatively good uniformity, and the magnetic strength change relative to the center point is less than 5%. The average received power of the system is greater than 800mW, and the PTE is up to 5.1%.

Effect of pulse width of middle-coil current on deformation behavior in electromagnetic tube forming under two-stage coils system

In the majority of electromagnetic tube forming system, the distribution of Lorentz force acting on tube is restricted and has poor controllability, which leads to the tube being unable to meet the requirement of manufacturing flexibly. A new electromagnetic tube-forming method based on the two-stage coils system, which consists of two coils and two independent capacitor banks, has been proposed to improve the distribution mode and controllability of Lorentz force. With higher deformation depth and less occurrence of cracking compared with the conventional one single-coil system; this method has been proved to be effective in improving the deformation behavior of tube in electromagnetic forming through experiments. However, the deformation behavior of tube in this forming method still needs further studies. In this paper, the effect of pulse width of middle-coil current on AA1060 aluminum tube deformation behavior under two-stage coil system is investigated through simulation model, which is based on the combination of current filament method and finite element method. Results show that the short pulse width of the middle-coil current can achieve larger deformation depth of tube under relatively small discharging energy, and the long pulse width of the middle-coil current has good performance in deformed profile. Moreover, the thickness reduction in the case of long pulse width of middle-coil current is less than the case of short pulse width of the middle-coil current under equal deformation depth of tube.

Multiplexed Supply of a MISO Wireless Power Transfer System for Battery-Free Wireless Sensors

Multi-input single output wireless power transmission (MISO-WPT) systems have decisive advantages concerning flexible receiver position in comparison to single coil systems. However, the supply of the primary side brings a large uncertainty in case of variable positions of the secondary side. In this paper, a compact multiplexed primary side electronic circuit is proposed, which includes only one signal generator, a passive peak detector, a communication module, and a compensation capacitor. The novel approach has been studied and evaluated for a MISO-WPT system having a 16 coils on primary side and one coil on secondary side having the double diameter. Results show that a standard microcontroller, in this case an STM32, is sufficient for the control of the whole system, so that the costs and the energy consumption are significantly reduced. An activation strategy has been proposed, which allows to determine the optimal transmitting coil for each position of the receiving coil and to switch it on. The time-to-start-charging at different positions of the receiving coil and different number of neighbors has been determined. It remains in all cases under 2.5 s.

Tube Electromagnetic Free Bulging Based on Internal Negative-External Positive Three-Coil System

Controlling the direction and profile of the electromagnetic force (EMF) is a key of improving the tube axial-uniformity and wall thickness during the electromagnetic forming process. In this regard, this article proposes a new tube electromagnetic-bulging topology using internal negative-external positive three-coil system. This structure is aimed at realizing effective bidirectional loading of axial and radial EMFs on the tube. An electromagnetic-structure coupling two-dimensional model is proposed to study the effect of the coil structure on the EF profile, bulging profile and the tube wall-thickness. The performance of the proposed method is compared with the traditional method through several performance metrics that include the electromagnetic force distribution cloud map, the tube bulging uniformity and its wall thickness. Numerical simulation results show that by changing the coil structure, the radial EMF profile can be effectively enhanced, and the free bulging contour of the tube can be further regulated. The additional axial EMF due to the proposed structure can promote the axial-flow of the material, thereby suppressing the reduction in the tube wall-thickness which is unavoidable using the traditional method. In comparison to the traditional single-coil system bulging, the maximum axial uniformity range of the tube is increased from 6.5mm to 35.2mm, and the wall thickness of the most severely thinned area is increased from 1.43mm to 1.77mm which verifies the effectiveness of the proposed method.

혈액 분류 작업을 위한 Cold Bench 개발에 관한 연구

The blood preparation is important for management and classification. Because the work bench for sorting blood is not produced domestically, we have developed a work bench to classify blood through this study. Single coil system was developed to control cooling efficiency and temperature distribution. And evaporator and heater were used to reduce condensate discharge. This allow us to maintain a constant temperature and the condensation remainder below 1L. This study is expected to expand to other bio-equipment development.

Enhanced Power-Delivered-to-Load Through Planar Multiple-Harmonic Wireless Power Transmission

In this brief, a method is presented to enhance the amount of power delivered to load (PDL) by making use of three-harmonic wireless power transmission while it does not occupy larger area than a conventional single-coil system. The proposed system consists of three inductive links each one tuned at a harmonic of the operating frequency. A single power amplifier supplies all of them. Therefore, the sum of the currents flowing through the secondary-side coils becomes almost square-wave and PDL will be 32.5% greater than that of a conventional single-coil system when both systems are supplied with the same voltage source. The parasitic inter-couplings between the coils deform the current waveform and make the PDL enhancement unachievable. Thus, a perpendicular 8-shaped coils structure is proposed to diminish these parasitic couplings and all the coils can be planar and coaxial. A laboratory prototype has been fabricated on printed circuit board operating at the frequency of 200 kHz. The experimental results confirm that the PDL is enhanced from 1.93 to 2.5 W by employing the proposed technique rather than a single-coil system.

Spatially-variant noise filtering in magnetic resonance imaging: A consensus-based approach

In order to accelerate the acquisition process in multiple-coil Magnetic Resonance scanners, parallel techniques were developed. These techniques reduce the acquisition time via a sub-sampling of the k-space and a reconstruction process. From a signal and noise perspective, the use of a acceleration techniques modify the structure of the noise within the image. In the most common algorithms, like SENSE, the final magnitude image after the reconstruction is known to follow a Rician distribution for each pixel, just like single coil systems. However, the noise is spatially non-stationary, i.e. the variance of noise becomes x-dependent. This effect can also be found in magnitude images due to other processing inside the scanner. In this work we propose a method to adapt well-known noise filtering techniques initially designed to deal with stationary noise to the case of spatially variant Rician noise. The method copes with inaccurate estimates of variant noise patterns in the image, showing its robustness in realistic cases. The method employs a consensus strategy in conjunction with a set of aggregation functions and a penalty function. Multiple possible outputs are generated for each pixel assuming different unknown input parameters. The consensus approach merges them into a unique filtered image. As a filtering technique, we have selected the Linear Minimum Mean Square Error (LMMSE) estimator for Rician data, which has been used to test our methodology due to its simplicity and robustness. Results with synthetic and in vivo data confirm the good behavior of our approach.

GPU implementation of non-local maximum likelihood estimation method for denoising magnetic resonance images

Magnetic resonance imaging (MRI) is a widely deployed medical imaging technique used for various applications such as neuroimaging, cardiovascular imaging and musculoskeletal imaging. However, MR images degrade in quality due to noise. The magnitude MRI data in the presence of noise generally follows a Rician distribution if acquired with single-coil systems. Several methods are proposed in the literature for denoising MR images corrupted with Rician noise. Amongst the methods proposed in literature for denoising MR images corrupted with Rician noise, the non-local maximum likelihood methods (NLML) and its variants are popular. In spite of the performance and denoising quality, NLML algorithm suffers from a tremendous time complexity $$O\left( {m^{3} N^{3} } \right)$$Om3N3, where $$m^{3}$$m3 and $$N^{3}$$N3 represent the search window and image size, respectively, for a 3D image. This makes the algorithm challenging for deployment in the real-time applications where fast and prompt results are required. A viable solution to this shortcoming would be the application of a data parallel processing framework such as Nvidia CUDA so as to utilize the mutually exclusive and computationally intensive calculations to our advantage. The GPU-based implementation of NLML-based image denoising achieves significant speedup compared to the serial implementation. This research paper describes the first successful attempt to implement a GPU-accelerated version of the NLML algorithm. The main focus of the research was on the parallelization and acceleration of one computationally intensive section of the algorithm so as to demonstrate the execution time improvement through the application of parallel processing concepts on a GPU. Our results suggest the possibility of practical deployment of NLML and its variants for MRI denoising.

PQUENCH-A 3-D quench propagation code using a logical coordinate system

A computer program was developed to model the effects of normal region propagation in the longitudinal direction (along the conductor) and in the two transverse directions in a superconducting coil in a multicoil system. A simulation of 3-D quench propagation in real space was done using a logical coordinate system in which each magnet is transformed into a single long conductor which is divided into finite-length elements. Since an element can be associated with geometry-related information such as the element length, the local magnetic field influence coefficients, and the relationship to adjacent elements in 3-D, the quench propagation in any type of 3-D configuration can be simplified to a 1-D problem. As the growth of the normal region is determined, the transient current decay is calculated based on increases in conductor temperature and resistance. This calculation can be done for multiple, inductively coupled systems through the use of a circuit analysis subroutine. The code logic is described, and results are given for calculated versus measured quench times in a single-coil system.

Single Coil Series Resonant Circuit for Pulsed Nuclear Resonance

This paper presents a description of and design optimization criteria for a series resonant single coil system suitable for use in pulsed nuclear magnetic or quadrupolar resonance. The design is adaptable to the frequency range 1–100 MHz, and permits both efficient use of transmitter power and signal reception with a high signal-to-noise ratio. An example of the design of a system to operate at 10 MHz is worked out and compared against the ideal case. An active damping circuit to speed the recovery following an rf pulse is also discussed.

A simple single-coil probe for pulsed nuclear magnetic resonance.

The circuit of the single-coil system for pulsed nuclear magnetic resonance is analysed in detail. A simple and effective probe with an active damper of pulse transients and with a preamplifier is described.

A PORTABLE PROTON PRECESSION MAGNETOMETER*

ABSTRACTThe paper describes a transistorised, portable proton precession magnetometer constructed for surface geophysical prospecting. Constructional and circuit details are furnished. The readout of the instrument is digital. The accuracy of measurement is ± 1 part in 20,000. The maximum gradient of the total field under which a satisfactory measurement can be made is about 1 gamma/cm. The sensing head uses a single coil system with distilled water as the proton sample.

A theoretical discussion of various possible aerial arrangements for rotating-beacon transmitters

In the following paper, three arrangements for a rotating-beacon transmitter are discussed from the theoretical point of view. These three systems are the single coil, the double-spacedcoil, and the Adcock aerial arrangement.In the case of the single-coil system it is shown thatunder night conditions, when wireless waves can be deflected from the upper ionized layer, the signal minimum as observed at the receiver can occur at such times during the rotation of the coil as to indicate an error in the observed bearing ranging up to 80 deg. It is shown that this error is of the same order as that observed on an ordinary direction-finder under similar conditions.The treatment of the arrangement of two co-planar spaced coils, as sometimes employed for directional reception, shows that, while the time of occurrence of the minimum giving the correct observed bearing remains unaltered during all conditions of night effect and downcoming waves, other secondary minima may be obtained under these conditions, the observed bearings on which maybe in error by the same amounts as those obtainable with the single-coil transmitter. As the observer at the receiver will, in general, be unable to distinguish between the main and the secondary minima, this double-coil system would appear to possess nearly the same liability to error as the single-coil system. The possibility of the two minima occurring close together will also detract from the accuracy of observation of the main minimum, even supposing it could be distinguished from the other.The third case to be considered is that proposed by Mr. C. E. Horton, viz. the use of the Adcock aerial system as a rotating transmitter. With this arrangement it is shown that a signal minimum is produced when the plane containing the pair of vertical aerials, or their equivalent in space, is perpendicular to the direction of the receiver. This minimum remains unaltered in thepresence of downcoming waves at night, and as no secondary minima occur it appears that this system will give correct bearings at all times when the signal is strong enough for observation.In searching for a type of rotating-beacon transmitter upon which the observed bearings are independent of night errors, it would appear that the Adcock arrangement is the most hopeful; and it is, therefore, proposed to consider this system in more detail from the practical standpoint.

A theoretical discussion of various possible aerial arrangements for rotating-beacon transmitters

In the following paper three arrangements for a rotating-beacon transmitter are discussed from the theoretical point of view. These three systems are the single coil, the double-spaced coil, and the Adcock aerial arrangement.In the case of the single-coil system it is shown that under night conditions, when wireless waves can be deflected from the upper ionized layer, the signal minimum as observed at the receiver can occur at such times during the rotation of the coil as to indicate an error in the observed bearing ranging up to 80 deg. It is shown that this error is of the same order as that observed on an ordinary direction-finder under similar conditions.The treatment of the arrangement of two co-planar spaced coils, as sometimes employed for directional reception, shows that, while the time of occurrence of the minimum giving the correct observed bearing remains unaltered during all conditions of night effect and downcoming waves, other secondary minima may be obtained under these conditions, the observed bearings on which may be in error by the same amounts as those obtainable with the single-coil transmitter. As the observer at the receiver will, in general, be unable to distinguish between the main and the secondary minima, this double-coil system would appear to possess nearly the same liability to error as the single-coil system. The possibility of the two minima occurring close together will also detract from the accuracy of observation of the main minimum, even supposing it could be distinguished from the other.The third case to be considered is that proposed by Mr. C. E. Horton, viz. the use of the Adcock aerial system as a rotating transmitter. With this arrangement it is shown that a signal minimum is produced when the plane containing the pair of vertical aerials, or their equivalent in space, is perpendicular to the direction of the receiver. This minimum remains unaltered in the presence of downcoming waves at night, and as no secondary minima occur it appears that this system will give correct bearings at all times when the signal is strong enough for observation.In searching for a type of rotating-beacon transmitter upon which the observed bearings are independent of night errors, it would appear that the Adcock arrangement is the most hopeful; and it is, therefore, proposed to consider this system in more detail from the practical standpoint.