Ring Core Research Articles

Reluctance Network Model of IPM Motor Representing Dynamic Hysteresis Characteristics for High-Accuracy Iron Loss Calculation Considering Carrier Harmonics

It is essential to establish a simple and practical method for quantitatively estimating the iron loss considering the dynamic hysteresis behavior to further improve the efficiency of electric machines. In a previous study, a novel simple magnetic circuit model representing the dynamic hysteresis characteristics was presented by incorporating a play model, one of the phenomenological dc hysteresis models, and a Cauer circuit, which can consider the skin effect. It was demonstrated that this magnetic circuit model could accurately calculate the hysteresis loops and iron loss even under PMW excitation for magnetic reactors made of several types of core materials in a short time. However, this method can only be used for an object with a simple shape, such as a ring core. Hence, this paper describes that the previously proposed magnetic circuit model is extended to a reluctance network analysis (RNA) to expand the application range. Furthermore, the proposed method was experimentally validated using an interior permanent magnet (IPM) synchronous motor driven by a PWM converter as the examination target.

Macromagnetic Approach to the Modeling in Time Domain of Magnetic Losses of Ring Cores of Soft Ferrites in Power Electronics

This article presents a new modeling approach capable of predicting Eddy current losses in soft ferrite cores as a function of the winding current. The proposed model is formulated in the time domain, which defines the magnetic core as a repeated regular structure of magnetic material grains and grain boundary in space. In this way, the homogenization process of the material is avoided, which is intended as the definition of a set of physical parameters of a continuous material equivalent to the real structure of the material. The distribution of the current density in the core and the core losses are computed utilizing the physical and geometric parameters of the grain of the magnetic material and of the grain boundary. To address the uncertainty in the definition of the physical and geometrical parameters of the magnetic grain and the grain boundary, a dedicated optimization procedure has been formulated, which takes into account the inaccuracy in the parameter measurement and the fact that the grain contour is an irregular surface and the boundary thickness is neither constant nor uniform. The performance assessment of the model is carried out over a broad frequency range using several experiments with a power amplifier and a dc–dc converter.

A Ring Core Fiber Sensor Based on Mach–Zehnder Interferometer for Transversal Force Sensing With Solvable Temperature Cross Sensitivity

In this work, we proposed a ring core fiber (RCF)-based all-fiber sensor used for transverse force sensing. The sensor is composed of 1-mm coreless fiber (CLF) and 2.5-cm RCF. Then, the coreless (CL)-ring core (RC) fiber structure is connected to two segments of single-mode fibers to form a Mach–Zehnder interferometer (MZI). The transmission spectrum of the MZI structure has a large extinction ratio (ER) of up to 20 dB with a free spectral range (FSR) of 9.3 nm. After the fabrication, the MZI sensor is packaged for force sensing at different temperatures. The different values of forces are applied on the fiber sensor, which are tuned from around 0.26 to 1.5 N/mm. With the increase of transverse force, the spectra of output signals show a linear redshift. The force sensitivity of the proposed MZI sensor reaches up to 4.109 nm/(N/mm) with a good linearity of 0.9824. By using a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2\times2$ </tex-math></inline-formula> matrix, the temperature cross sensitivity can be extracted. The proposed force sensor based on the MZI fiber structure shows great potential applications in the field of structural health monitoring and supercapacitor safety detection.

Mode conversion between fibers with different refraction index distribution based on adiabatically tapered structures.

Different fibers generally have different mode characteristics so their connections in many practical applications often require mode conversion. The feasibility of mode conversion between fibers with different refractive index distributions based on adiabatically tapered structures is theoretically analyzed. The first kind of mode conversion is between ring core fiber and convex core fiber; the second kind is between multicore fiber and single-core fiber. Three common tapered structures are investigated: tapered core, diffused core, and tapered cladding. The analysis results show that mode conversion by a tapered structure is not suitable for all the modes for a ring core fiber and a convex core fiber; however, it can be accomplished for multicore fiber and single-core fiber.

High sensitivity all-fiber bend sensor based on modal interferences in a ring core fiber

We proposed and experimentally demonstrated an all-fiber sensor for measuring bend with high sensitivity based on a ring core fiber (RCF) modal interferometer. The sensor was fabricated by splicing a segment of RCF between two pieces of multimode fiber (MMF) and single-mode fiber (SMF) at the ends of the MMF as lead-in and lead-out. Due to the first segment of the MMF, the transmitted light is coupled into the ring core, silica center, and cladding of the RCF, exciting multiple modes in the RCF. By the modal interferences in the structure, bending sensing can be realized by interrogating the intensity of the interference dip. Experimental results show a high bending sensitivity of -25.63 dB/m-1 in the range of 1.0954 m-1 to 1.4696 m-1. In addition, the advantages of the bend sensor, such as small size, low temperature sensitivity, and simple fabrication process, can be used for curvature measurement in building health monitoring.

Accurate Mode Decomposition for Ring Core Fibers Based on Deep Learning

Accurate Mode Decomposition for Ring Core Fibers Based on Deep Learning

Analysis and Experimental Investigation of High-Frequency Magnetic Flux Distribution in Mn-Zn Ferrite Cores

This article presents a comprehensive investigation of the high-frequency magnetic flux distributions in manganese-zinc ferrite ring cores. New experimental characteristics are presented and used in the flux modeling. The flux distribution is predicted by a one-dimensional analytical model, a transmission-line model, and finite-element analysis. The models are used to investigate the high-frequency effects, such as skin depth and dimensional resonance. A complete experimental validation is presented. The nonuniform magnetic flux distributions are experimentally validated for two Mn-Zn materials: 3F36 and 3E10. The low permeability 3F36 material performance can be significantly degraded by dimensional resonance. However, the high permeability 3E10 material degrades due to the skin effect. The presented analytical methods show a very good correlation with the measurements.

Accurate and noise-robust mode decomposition by analyzing the intensity distribution of a few-mode ring core fiber

Accurate and noise-robust mode decomposition by analyzing the intensity distribution of a few-mode ring core fiber

The theoretical design of manganese catalysts with a Si-N-Si-C-Si-C six-membered ring core-based bowl-shaped quadridentate ligand for the hydrogenation of CO/CN bonds.

Herein, a new series of bowl-shaped quadridentate ligands with a Si-N-Si-C-Si-C six-membered ring core and their manganese catalysts were designed using the density functional theory (DFT) method for the hydrogenation of unsaturated CX (XN, O) bonds. The frameworks of these ligands named by LYG (LYG = P(R1)2CH2Si(CH2)(CH3)NSi(CH3)(CH2Si(CH3)CH2P(R3)2)CH2P(R2)2) have a Si-N-Si-C-Si-C six-membered ring core at the bottom of the bowl structure and each Si atom links with one phosphorus arm (-CH2PR2). The Mn catalyst Mn(CO)-LYG was constructed to catalyze the hydrogenation of CO/CN bonds. The calculated results indicate that due to the bowl-shaped structure of LYG quadridentate ligands, these Mn catalysts could be advantageous not only in the tuneup of catalytic activity and stereoselectivity by modifying three phosphorus arms but also in the homogeneous catalyst immobilization by linking with the Si-N-Si-C-Si-C six-membered ring core using different supports. This work might provide theoretical insights to design new framework transition-metal catalysts for the hydrogenation of CX bonds.

112 orbital angular momentum modes amplification based on a 7RC-EDF with low differential mode gain.

We demonstrate 112 orbital angular momentum (OAM) modes amplification based on a designed and fabricated 7-ring-core erbium-doped fiber (7RC-EDF). The differential mode gain (DMG) of all the intra-core OAM modes in 7RC-EDF is effectively reduced. The DMG of intra-core modes can be suppressed by the high overlap between the signal modes and pump fundamental mode resulting from the designed structures of the ring core assisted by a trench. The differential gain of the inter-core can be controlled by the power of the core-pump configuration as well. With an experimentally optimized scheme of the pump power of each core, a record low-DMG of 2.8 dB among the 112 OAM modes (16-OAM-mode per core in the 7-core) is achieved at a wavelength of 1550 nm. The obtained favorable performance of the 112 OAM modes based on 7RC-EDF indicates it may promote a long-haul high-density OAM modes multiplexed transmission.

High birefringence low loss low dispersion ring core photonic crystal fiber on terahertz band

Abstract A novel high birefringence low loss photonic crystal fiber (PCF) based on terahertz (THz) band is proposed in this paper. By constructing ring cores in core air holes and innermost cladding air holes, the characteristics of the PCF were studied in the band of 0.6–1.2 THz. The simulation results show that the birefringence characteristic of the fiber can reach 0.0514 at 0.6 THz under the optimal parameters. When working at an operating frequency of 1 THz, not only the birefringence characteristic is maintained at 0.044, but also the confinement loss is as low as about 10−6 dB/m, the dispersion of 0.272 ps/THz/cm and 0.49 ps/THz/cm, the effective mode field area reaches 0.981 μm2 and 0.745 μm2, and the single-mode operating characteristics can be maintained in the entire studied band.

Alternation of asphaltene binding arrangement in the presence of chemical inhibitors: Molecular dynamics simulation strategy

Asphaltene deposition is one of the challenging issues in petroleum production and transportation. Chemical inhibitors are commonly employed to mitigate the asphaltene aggregation, which is the primary stage in controlling asphaltene deposition. Design and selection of an effective chemical inhibitor have always been a challenge for the industry, considering substantial variations in characteristics and structures of asphaltene and petroleum. The chemical inhibitors interact with the asphaltene aggregation by alternating their binding arrangement, which is a key factor in the aggregate stability. Molecular studies that can reveal the main mechanisms are still scarce, and the available investigation techniques in this area need significant improvements. Therefore, in this work, molecular dynamics (MD) simulation is employed as a cost-effective and reliable method to study the impact of chemical inhibitors on the binding arrangement of two asphaltene structures. One asphaltene structure contains a hydroxyl group and pyridinic nitrogen in its polyaromatic core, while another lacks both groups. The chemical inhibitors are octylphenol (OP), 1-butyl-3-methylimidazolium bromide ([BMIM][Br]), and 1-butyl-3-methylimidazolium chloride ([BMIM][Cl]). The simulation results show OP cannot stop the quadrupole–quadrupole interactions between the asphaltenes since the force between OP’s benzene ring and asphaltene polyaromatic core is weaker than the force between the two polyaromatic cores. Nevertheless, OP forms a hydrogen bond with the asphaltene and prevents asphaltene molecules from approaching each other by providing steric hindrance around the molecules. As a result, OP does not show a promising potential to reduce the parallel stacking, especially for the asphaltene with no hydrogen bond potential, while it relatively reduces the T-shape arrangement for both asphaltenes. Ionic liquids (ILs) beat the quadrupole–quadrupole interactions between the asphaltene cores with cation-quadrupole force and notably reduce the parallel stacking. They also lower the number of T-shape binding arrangements between the asphaltene molecules. This research reveals the mechanism for the studied inhibitors to interfere with the asphaltene aggregation based on their functional groups. We introduce new criteria to distinguish different arrangements. The binding arrangement of polyaromatic compounds (such as asphaltene) are not only important in the petroleum industry but also play a crucial role in designing optical and electronic nanodevices. The introduced approach is a new pathway to improve the design of chemical materials to either inhibit or promote aggregation by changing binding arrangement of polyaromatic compounds.

Mode manipulation in a ring–core fiber for OAM monitoring and conversion

Abstract The monitoring and conversion of photonic orbital angular momentum (OAM) play fundamental and important roles for both classic and quantum technologies, especially in low-loss transmission media such as ring-core fibers (RCFs), which make many OAM applications practical or vastly more flexible. However, in a RCF, the modes associated with different OAM states are highly overlapping due to the circular refractive index distribution structure, which makes it difficult to distinguish and monitor the OAM modes and in turn limits its inline conversion. Here, we report the first experimental realization of mode monitoring in a RCF using mode filters (MFs), which takes advantage of the difference in the mode adiabatic evolution and the higher-order mode cutoff conditions in tapered RCFs. Different-order OAM can be filtered using MFs with different geometric parameters, as demonstrated by the linearly polarized mode intensity. Combined the mode manipulations in RCF and single-mode fiber, the fundamental mode coupling efficiency can reach 90%, the RCF mode conversion monitoring through inline transmission spectrum evolution can be realized, and the inline fabrication of RCF grating, which couples one mode to a desired mode, can be demonstrated by the fabricating process of three long-period fiber gratings. The mode conversion efficiency between 0-order and 1, 2- or 3-order OAM modes exceeds 96%. Our work provides an efficient approach to monitor and convert OAM modes in higher-order mode supporting RCFs and even other special fibers and further promotes the improvement of the capacity of OAM transmission in RCFs.

A novel mode-division (de)multiplexer with degenerate modes output for MIMO-FREE applications

In this study, we propose a novel three-dimensional architecture mode (de)multiplexer with degenerate modes output using a pure silica FMF ring core transmission channel, which solves the problem caused by random mode rotation and can be used in multiple-input multiple-output free (MIMO-FREE) applications such as data center application in the future. By using the pure silica FMF ring core transmission channel and larger effective refractive index difference, the performance with low loss, high extinction ratio (ER) and low crosstalk is achieved. The main channel with a few-mode fiber (FMF) ring-core structure supports the modes LP01, LP11, and LP21, and the large effective refractive index difference between each mode in the core ensures low crosstalk characteristics between the modes. Using the pure silica core channel can effectively reduce propagation attenuation and fusion loss. Our proposed MUX/DEMUX with degenerate modes output is achieved when the degenerate modes LP11a/LP11b and LP21a/LP21b are transmitted as two independent mode signals, which can be used in MIMO-FREE applications. The extinction ratios (ERs) of the degenerate modes LP11 and LP21 are kept above 31.66 dB and 24.43 dB, respectively, and the ER of mode LP01 is kept above 38.72 dB in the C band. The coupling efficiency of mode LP01 is approximately 0 dB, which is almost unchanged with the increase of the wavelength. The coupling efficiency of LP11 is higher than −3.49 dB and that of LP21 is higher than −7.24 dB in the whole C-band. At 1550 nm, the coupling efficiencies of modes LP01, LP11, and LP21 are −0.002 dB, −0.052 dB, and −0.178 dB, respectively. The coupling efficiency and ER of LP01 mode are the best, and those of the degenerate mode LP11 are always better than those of mode LP21. Our proposed MUX/DEMUX achieves low crosstalk and high ER performance and solves the problem caused by the degenerate modes rotations during transmission.

Photoredox-based late-stage functionalization in SAR study for in vivo potent glucosylceramide synthase inhibitor

Glucosylceramide synthase (GCS) has drawn much attention as an attractive protein target in the disease pathways of Parkinson’s Disease (PD) and lysosomal storage disorders, such as Gaucher’s Disease (GD). In previous our study, T-036 and its analogue, 2a, were discovered as novel GCS inhibitors. To further improve activity of this chemical series, SAR was investigated on the fused pyridyl ring core of 2a by employing a photoredox reaction that significantly reduced synthetic demand. Herein, we successfully applied the decarboxylation C–H alkylation photoredox reaction to introduce a wide variety of substituents at the 6-position of the fused pyridine core scaffold. This quick SAR acquisition facilitated the swift identification of the potent GCS inhibitors 2b (IC50 = 5.9 nM) and 2g (IC50 = 3.6 nM). Moreover, 2b exhibited superior in vivo potency to that of our previously reported lead compound, T-036.

A measurement framework using THz Time-Domain sensing for wood quality assessment across tree ring samples

To investigate the effectiveness of selective tree improvement work, an accurate and calibration-free framework based on THz time-domain sensing for intrinsic wood quality traits assessment was specifically designed for tree ring core sample analysis. This study contains a global phase unwrapping strategy, effective medium theory (EMT)-based measurement, combined measurement, and resolution enhancement, all of which aim to solve and discuss several challenges in THz time-domain sensing. Namely, the global phase unwrapping strategy eliminates the global jumps in phase difference by analysing the principle of jump generation; EMT-based THz measurement can assess properties of hundreds of consecutive sampling points on wood cores without model training; the combined measurement adjusts relative permittivity and dielectric loss relative to one other in a coordinate system; the resolution enhancement converts 3-D PSF into 1-D PSF, and extracts attenuation to achieve resolution enhancement of target properties. The results show that the global phase unwrapping strategy has the potential to deal with phase differences of both homogeneous and heterogeneous samples and can be considered a general unwrapping method. All R2 obtained by combined measurement are higher than that obtained by separate relative permittivity measurement. The resolution enhancement can achieve more accurate and faster measurement. The framework presented here offers significant potential in promoting the application of THz in wood quality traits assessment by providing a low-cost and high precision analysis system.

Dual-channel fiber-optic surface plasmon resonance sensor with cascaded coaxial dual-waveguide D-type structure and microsphere structure

To address the restriction of fiber-optic surface plasmon resonance (SPR) sensors in the field of multi-sample detection, a novel dual-channel fiber-optic SPR sensor based on the cascade of coaxial dual-waveguide D-type structure and microsphere structure is proposed in this paper. The fiber sidepolishing technique converts the coaxial dual-waveguide fiber into a D-type one, and the evanescent wave in the ring core leaks, generating a D-type sensing region; the fiber optic fused ball push technology converts the coaxial dual waveguides into microspheres, and the stimulated cladding mode evanescent wave leaks, producing the microsphere sensing region. By injecting light into the coaxial dual-waveguide middle core alone, the sensor can realize single-stage sensing in the microsphere sensing area; it can also realize dual-channel sensing in the D-type sensing area and microsphere sensing area by injecting light into the ring core. The refractive index measurement ranges for the two channels are 1.333–1.365 and 1.375–1.405, respectively, with detection sensitivities of 981.56 nm/RIU and 4138 nm/RIU. The sensor combines wavelength division multiplexing and space division multiplexing technologies, presenting a novel research concept for multi-channel fiber SPR sensors.

Hyper Parameters Optimization for Effective Brain Tumor Segmentation with YOLO Deep Learning

In the field of neuroimaging, differential diagnosis of brain tumour primarily relies on the visual appearance of the tumor in the MRI. For better analysis of brain tumours segmentation of tumour ROI is indispensable. The objective of this work is to develop a deep network for brain tumour segmentation using YOLO with T1C+ High grade and FLAIR low grade tumour images from the BRATS dataset. As the hyper parameters play a crucial role in the efficacy of the CNN, an exhaustive search is made to arrive at the optimal hyper parameters. The number of anchor boxes, mini batch size and the learning algorithm are carefully evaluated to arrive at the optimal values. The visual analysis of segmentation proves the effectiveness with 4 anchor boxes, mini batch size 16 and Adam optimizer. The mean average precision value of 0.9688 and recall value of 0.9841 is obtained for HGG segmentation. The mean average precision value as 0.8435 and recall value of 0.8552 is obtained for LGG segmentation. The accuracy of the tumor detector computed with Mean IoU score is 100% for HGG and 98% for LGG tumor images. The tumor image segmented using YOLO is further subjected to histogram and region growing techniques to segment the ring and lesion core of the brain tumor which may be used for further analysis of benign and malignant tumor. As YOLO CNN could fix the bounding box with highest accuracy, the traditional skull stripping pre-processing techniques can be skipped for tumor segmentation.

High-order orbital angular momentum mode conversion based on a chiral long period fiber grating inscribed in a ring core fiber.

A chiral long period fiber grating (CLPFG) was designed according to the phase-matching condition and conservation law of angular momentum, and was inscribed in a ring core fiber (RCF). This CLPFG was used to directly excite the ±2nd- and ±3rd-order orbital angular momentum (OAM) modes. The coupling efficiency of the OAM mode is up to 98.7% and the insertion loss is within 0.5 dB. The uniformity of the annular mode intensity distribution, polarization characteristics, and the mode purity of coupled OAM modes were investigated in detail. Results show that the coupled high-order OAM modes possess a relative uniform annular intensity distribution, its mode purity is up to 93.2%, and the helical phase modulation is independent on the polarization state of incident light. These results indicate that the RCF-based CLPFG is an ideal OAM mode converter for future high-capacity optical fiber communication systems.

Inkjet-printed Mn-Zn ferrite nanoparticle core for fluxgate

Non-planar fluxgate sensors measuring the magnetic fields in the μT range are required for electric current, position, and torque transducers. We report the first sensor based on an inkjet-printed 17 mm diameter ring core. The sensor wide open-loop linear range of ± 1.5 mT allows to operate it without feedback. We describe the preparation of the very stable magnetic ink based on citrate-stabilized 13 nm diameter Mn-Zn ferrite nanoparticles that occur in superparamagnetic regime at room temperature. By printing 100 layers the total thickness of the inkjet-printed core was 2.2 µm. The achieved sensitivity was 10 mV/mT for 25 kHz excitation frequency.