Soft Cores Research Articles

Enhanced Magnetic Properties of FeSiAl Soft Magnetic Composites Prepared by Utilizing PSA as Resin Insulating Layer

Thermosetting organic resins are widely applied as insulating coatings for soft magnetic powder cores (SMPCs) because of their high electrical resistivity. However, their poor thermal stability and thermal decomposition lead to a decrease in electrical resistivity, thus limiting the annealing temperature of SMPCs. The large amount of internal stress generated by soft magnetic composites during pressing must be mitigated at high temperatures; therefore, it is especially important to find organic resins with excellent thermal stabilities. In this study, we prepared SMPCs using poly-silicon-containing arylacetylene resin, an organic resin resistant to high temperatures, as an insulating layer. With 2 wt % PSA as an insulating layer and annealed at 700 °C for 1 h, the FeSiAl SMPCs achieved the best magnetic properties, including the lowest core loss of 184 mW/cm3 (measured at 0.1 T and 50 kHz) and highest permeability of 96.

Analysis of auxetic core sandwich beams subjected to transversely localized loads using two-dimensional symplectic elasticity approach

It is well known that sandwich structures containing low-density soft cores are susceptible to transversely localized loads. However, multi-parameter foundation models of the sandwich cores are extremely simplified when the structures are composed of auxetic materials, whose Poisson’s ratios play very important roles in the face–core interaction. In this study, a two-dimensional symplectic elasticity model of a beam–foundation system representing sandwich beams subjected to normal surface tractions is formulated. The effects of the foundation properties, including Poisson’s ratio ranging from positive to negative, are presented. The proposed technique is beneficial for the potential usage of auxetic core materials.

Enhanced high frequency properties of FeSiBPC amorphous soft magnetic powder cores with novel insulating layer

Fe-based amorphous magnetic powder cores (AMPCs) with excellent comprehensive properties were successfully fabricated via using the uniform double insulating layer core-shell structured FeSiBPC/Fe3O4@Epoxy resin (EP). The effects of the in-situ hydrothermal oxidized time on the magnetic properties of the AMPCs have been systematically investigated on the basis of the growth mechanism of the insulating layer of spherical amorphous powder in alkaline environment. The hydrothermal oxidation process could well ensure the uniformity of the oxide layer composed of Fe3O4 nanoparticle. The evolution of the insulating layer is a process of homogeneous nucleation and growth at different hydrothermal oxidation time. After 10 h of hydrothermal oxidation, a thin and dense layer composed of Fe3O4 nanoparticle was formed on the surface of the amorphous powder. As a consequent, the FeSiBPC AMPCs exhibit excellent performance such as stable effective permeability of 49.5 at 2 MHz, a very low core loss of 187 mW/cm3 at 100 kHz@0.05 T and high-quality factor of 160 at 600 kHz. The results indicate that the thickness of the Fe3O4 insulating layer can be completely controlled via the reaction parameters, and can effectively suppress the eddy current loss, which is promising for high-frequency electromagnetic systems.

Microstructural Changes and Magnetic Properties of Nanostructured Fe-Si-B-Cu Ribbon Cores Containing a Small Amount of Ca and Zr

Nanocrystalline Fe-Si-B-Nb-Cu Finemet alloys show low saturation magnetic flux density compared to amorphous Fe-Si-B alloys. In the Fe-Si-B-Cu base amorphous alloys, Cu atoms form clusters which act as heterogeneous nucleation sites for α-Fe crystals. The addition of Ca element atoms, distributed along grain boundaries, helps inhibit grain growth and increase resistivity. These alloys can be crystallized into fine nanograins through proper heat treatment, with increased saturated flux density and decreased core loss. According to previous studies, the addition of Zr element can also reduce nanograin size and suppress grain growth by its distribution mainly along the grain boundaries. In this experiment, the effects of added Ca and Zr on the microstructural changes and magnetic properties of Fe-Si-B-Cu were evaluated in detail. Fe-Si-B-Cu alloys containing Ca, and Zr elements were melt-spun to make rapidly solidified ribbons ~20 μm in thickness. The ribbons were then wound into toroidal shaped ribbon cores and heat treated to obtain the nanocrystalline soft magnetic ribbon cores. The microstructure was observed using TEM, and the magnetic characteristics were evaluated using an B-H meter and impedance analyzer. Based on the results, the FeSi-B-Cu ribbon core containing 0.037 wt.% Ca and 1.68 wt.% Zr was determined to have the lowest core loss among the alloys, when annealed at 440 <sup>o</sup>C for 30 min. It was also confirmed that the added Ca and Zr elements were distributed along the grain boundary, and suppress the growth of crystals. In conclusion, the addition of minor elements Ca and Zr to the nanocrystalline ribbon core was very effective at reducing core loss, and the saturated flux density of the core also increased pronouncedly compared to the Fe-Si-B-Nb-Cu Finemet alloys.

The enhanced magnetic properties of FeSiCr powder cores composited with carbonyl iron powder

Toroid-shaped Fe-based soft magnetic powder cores (SMPCs) were prepared by cold pressing commercial FeSiCr and carbonyl iron powder (CIP) insulated with epoxy resin. The effect of the CIP mass ratio on the magnetic properties of powder cores, which included the dependences of the effective permeability (μe), DC bias characteristic, and core loss (Pcv), was investigated. By optimizing the CIP content, the μe of the magnetic powder cores reaches 31 when the CIP content is 30 wt%, and it exhibits a stable permeability in the frequency range up to 1 MHz. Meanwhile, the DC bias characteristic increases to 78%, and the Pcv is minimized to 1684 mW/cm3, which is reduced by 15% at 50 mT and 250 kHz.

High-Performance Accurate and Approximate Multipliers for FPGA-Based Hardware Accelerators

Multiplication is one of the widely used arithmetic operations in a variety of applications, such as image/video processing and machine learning. FPGA vendors provide high-performance multipliers in the form of DSP blocks. These multipliers are not only limited in number and have fixed locations on FPGAs but can also create additional routing delays and may prove inefficient for smaller bit-width multiplications. Therefore, FPGA vendors additionally provide optimized soft IP cores for multiplication. However, in this work, we advocate that these soft multiplier IP cores for FPGAs still need better designs to provide high-performance and resource efficiency. Toward this, we present generic area-optimized, low-latency accurate, and approximate softcore multiplier architectures, which exploit the underlying architectural features of FPGAs, i.e., lookup table (LUT) structures and fast-carry chains to reduce the overall critical path delay (CPD) and resource utilization of multipliers. Compared to Xilinx multiplier LogiCORE IP, our proposed unsigned and signed accurate architecture provides up to 25&#x0025; and 53&#x0025; reduction in LUT utilization, respectively, for different sizes of multipliers. Moreover, with our unsigned approximate multiplier architectures, a reduction of up to 51&#x0025; in the CPD can be achieved with an insignificant loss in output accuracy when compared with the LogiCORE IP. For illustration, we have deployed the proposed multiplier architecture in accelerators used in image and video applications, and evaluated them for area and performance gains. Our library of accurate and approximate multipliers is opensource and available online at <uri>https://cfaed.tu-dresden.de/pd-downloads</uri> to fuel further research and development in this area, facilitate reproducible research, and thereby enabling a new research direction for the FPGA community.

Microstructure and magnetic properties of SiO2/FeCoNiSi0.25 high-entropy alloy with a core/shell structure

This study aimed to improve the mechanical and soft magnetic properties of HEAs with core–shell structure. Core-shell structured SiO2 particles and interparticle insulative SiO2/FeCoNiSi0.25 soft cores were prepared by in situ chemical deposition combined with the following spark plasma sintering (SPS) process. The structure of the high-entropy alloy (HEA) formed was a single face-centered-cubic solid-solution phase. The Ms and Hc of FeCoNiSi0.25 HEA powders without and with SiO2 shell were 103.41 emu/g and 85.96 emu/g, and 177.60 Oe and 184.12 Oe, respectively. On the contrary, the Ms and Hc of the bulk FeCoNiSi0.25HEAs (SPS-ed) without and with SiO2 shell were 135.92 emu/g and 142.8 emu/g, and 5.92 Oe and 167.83Oe, respectively. The magnetic properties of SiO2/FeCoNiSi0.25 HEAs (SPS-ed) were significantly stronger than those of SiO2-free FeCoNiSi0.25, indicating that the coupling phenomenon between magnetic crystals existed.

An alternative finite strain elastoplastic model applied to soft core sandwich panels simulation

An alternative elastoplastic model based on the Flory’s right Cauchy-Green stretch tensor decomposition is proposed and applied to model soft cores of sandwich panels. It does not follow usual methodologies as the additive decomposition or the Kröner-Lee multiplicative decomposition of strains. It is based on an important hyperelastic relation, Flory’s decomposition, from which the total strain is separated in two isochoric and one volumetric parts. Using this decomposition, the volumetric strain energy continues to be elastic during all elastoplastic analysis and the isochoric parts are managed to produce the plastic evolution. As a consequence of Flory’s decomposition, the plastic flow direction is known and independent of the yielding surfaces. Moreover, it provides the well known deviatoric nature of plastic strains. For validation purposes, the resulting formulation is implemented using a special 3D prismatic element in a geometrical nonlinear positional FEM computational code. The achieved numerical results are compared with literature experimental data of soft core laminated structural elements.

A high performance scalable fuzzy based modified Asymmetric Heterogene Multiprocessor System on Chip (AHt-MPSOC) reconfigurable architecture

This Ensuing generation of FPGA circuit tolerates the combination of lot of hard and soft cores as well as devoted accelerators on a chip. The Heterogene Multi-Processor System-on-Chip (Ht-MPSoC) architecture accomplishes the requirement of modern applications. A compound System on Chip (SoC) system designed for single FPGA chip, and that considered for the performance/power consumption ratio. In the existing method, a FPGA based Mixed Integer Programming (MIP) model used to define the Ht-MPSoC configuration by taking into consideration the sharing hardware accelerator between the cores. However, here, the sharing method differs from one processor to another based on FPGA architecture. Hence, high number of hardware resources on a single FPGA chip with low latency and power targeted. For this reason, a fuzzy based MIP and Graph theory based Traffic Estimator (GTE) are proposed system used to define New asymmetric multiprocessor heterogene framework on microprocessor (AHt-MPSoC) architecture. The bandwidths, energy consumption, wait and transmission range are better accomplished in this suggested technique than the standard technique and it is also implemented with a multi-task framework. The new Fuzzy control-based AHt-MPSoC analysis proves significant improvement of 14.7 percent in available bandwidth and 89.8 percent of energy minimized to various traffic scenarios as compared to conventional method.

Great Reduction in Pressing Pressure by Particle Grading for Fe-Si-Al Soft Magnetic Powder Cores with Good Low-Frequency Magnetic Properties

Great Reduction in Pressing Pressure by Particle Grading for Fe-Si-Al Soft Magnetic Powder Cores with Good Low-Frequency Magnetic Properties

Soc-approach for Safety-oriented Multi-channel Communication in Industrial Application of Human-robot-collaboration (HRC)

The importance of human-robot collaboration systems in industrial applications has increased due to the orientation towards the smart factory approach. To ensure the safety of such systems, collision avoidance techniques based on millimeter-wave radar sensors are used. Safe communication between the robot and the radar sensor is ensured by using the safety system on a chip based on 1oo2D architecture. The design and prototyping of a multi-channel communication FPGA-based development board is presented. Furthermore, the FPGA implementation of SoC with multiple Ethernet MAC interfaces based on various soft cores is demonstrated.

Modelling of the magnetization reversal of nanocomposites consisting of core–shell particles

We performed large-scale micromagnetic simulations on core–shell particle systems for and nanocomposites, where both magnetically hard and soft materials were considered as the core or shell materials of these particles. A detailed analysis of the influence of structural properties and exchange core–shell coupling within the same particle on the magnetization reversal of a nanocomposite was carried out, revealing different remagnetization scenarios in terms of the evolution of magnetization distributions in soft magnetic cores. The optimal nanocomposite compounds with respect to the energy product of material were predicted.

Fe-6.5 wt%Si Powder Cores with Low Core Loss by Optimizing Particle Size Distribution

The effect of different particle size distribution of Fe-6.5 wt%Si powder on the microstructure and soft magnetic properties of the corresponding soft magnetic powder cores (SMPCs) was investigated. By optimizing particle size distribution, the density of SMPCs increased and the total core loss significantly decreased. According to the result of loss separation, density of SMPCs is inversely proportional to hysteresis loss, while with increasing the content of the fine particles, the eddy current loss significantly decreased. It was found that with magnetic powder of particle size-grading as 10%, 10%, 60%, and 20% for particles with size between −75 to +38, −38 to +23, −23 to +13, and −13 μm, respectively, the Fe-6.5 wt%Si SMPCs exhibit optimal comprehensive magnetic performances with the effective permeability of about 60, the percent permeability at 100 Oe is up to 70%, and the lowest core loss of 553 mW/cm3.

Dynamics properties of multi-layered composite sandwich doubly-curved shells

The present work deals with the dynamics properties of two kinds of multi-layered composite sandwich doubly-curved shells with two-layered viscoelastic cores based on first order shear deformation theory (FSDT). The Hamilton’s principle is adopted to deduce the equations of motion that govern the free vibrations of the sandwich doubly-curved shells. The vibration frequencies and associated loss factors of shells are obtained by solving these equations as an eigenvalue problem based on the Navier method. Then, the validity of present solutions is confirmed comparing with those available in the published literatures. Next, the change rules of frequencies and loss factors with structural parameters are evaluated and presented graphically. New results for dynamics properties of multi-layered composite sandwich doubly-curved shells with two-layered soft cores are proposed for the first time.

S2925 Gastric Splenosis Mimicking Gastrointestinal Stromal Tumor

INTRODUCTION: Translocation of splenic tissue in patients after traumatic spleen injury or splenectomy is called splenosis. Gastric splenosis is a rare presentation that can be mistaken for gastrointestinal stromal tumors. Patients are usually asymptomatic and do not require surgical intervention. CASE DESCRIPTION/METHODS: We present a case of a 68-year old male patient with previous history of surgical splenectomy after traumatic splenic rupture, who underwent routine upper endoscopy for evaluation of dysphagia. Endoscopic exam of the stomach revealed an incidental finding of a submucosal gastric nodule. On endoscopic ultrasound exam, the lesion was suggestive of a Gastrointestinal stromal tumor (GIST) originating from layer 4. A core biopsy was obtained from the nodule which was consistent with Gastric splenosis. DISCUSSION: The differentiation of gastric splenosis from other gastric lesions such as GIST is important since asymptomatic patients with gastric splenosis do not need to undergo surveillance or surgical resection. It should be suspected especially in patients with history of splenectomy or splenic rupture. EUS guided core biopsy can help confirm the diagnosis and differentiate it from GIST.Figure 1.: Core biopsy of the lesion showing multiple soft tan-white tissue cores composed of blood and eosinophilic stroma with eosinophils, macrophages, plasma cells and neutrophils consistent with Gastric splenosis.Figure 2.: Submucosal papule which appears to be originating from within muscularis propria, layer 4.Figure 3.: Submucosal papule in the fundus of the stomach.

Enveloping Fe–12%Al atomized powders in selectively-oxidized insulating films for soft magnetic composite (SMC) cores

Fe-12 wt%Al gas atomized powders were enveloped in a uniform Al2O3-containing oxide film by heat-treatment of a mixture of Fe–Al and Mg(OH)2 powders at 900 °C for 1 h in static hydrogen atmosphere. In this novel method using a semi-closed system without adding any oxidants, water vapor generated by decomposition of Mg(OH)2 was used as an oxidant to selectively oxidize aluminum in the Fe-12 wt%Al alloy. Most of the generated water vapor was consumed to form the Al2O3 film and the thickness of the insulating film could be controlled in the tens of nanometers range by controlling the amount of added Mg(OH)2 in the mixture. Fe–12%Al powders enveloped in around 50 nm thick oxide films could be applied to make reasonably high-performance soft magnetic composite cores, because the high temperature heat-treatment up to 900 °C was possible and hence easily relieved the strain energy generated when shaping the cores.

Evaluation of 3D Printed Cobalt Iron Cores for Filter Inductors

This article presents a timely report on 3D printed cobalt iron (CoFe) soft magnetic cores enabled by the latest advances of additive manufacturing technologies. The feasibility of 3D printing CoFe magnetic cores is demonstrated in a current-ripple-filtering line inductor for power electronics applications. A like-for-like comparison is conducted between the 3D printed solid core and a commercial laminated core with the identical outer geometries to benchmark the former. Performance of the cores is evaluated based on assembled inductors regarding two key high-frequency characteristics, the inductance and the core losses. The results show that the effective permeability of the 3D printed core reduces rapidly with the increase of frequency, due to the low effective resistivity and consequently prominent eddy currents. When the functional equivalent is achieved, i.e., the same inductance for filtering switching-frequency current ripples, the inductor with 3D printed CoFe cores shows five times larger core losses compared with the commercial laminated core.

Coil and core design for inductive energy receivers

The design of coil/core transducers is important for maximizing the power density of inductive energy receivers for both inductive energy harvesting and power transfer. In this work, we present a study of core and coil performance, based on a simulated flux distribution corresponding to aircraft applications. The use of funnel-shaped soft magnetic cores boosts magnetic flux density by flux concentration and allows the use of a smaller diameter coil. This reduces the transducer mass as well as the coil resistance (RCOIL), thereby increasing the available power density. Analysis and simulation shows a fifty-fold power density increase from moderate funneling and another two-fold increase by coil size optimization. Results are compared with experimental measurements which demonstrate a 31 μW/g power density from alternating environmental magnetic fields in the 10 μT/360 Hz range.

On inefficiency of the shape memory alloys in dynamically loaded sandwich plates with structural damping: New 3D zigzag-viscoelasticity theory and asymmetric transformations

Abstract The important claim that the presence of the structural damping considerably lessens or even eliminates the effectiveness of the embedded shape memory elements in the dissipation of the vibration/impact energies of the structures, is stated and proven here for the first time. The finite-element-based governing equations of thick composite sandwich plates with homogeneous/FG soft viscoelastic cores and embedded SMA wires are derived based on a new hyperbolic SMA-zigzag sandwich plate theory that considers the transverse flexibility. The tension-compression asymmetry of the SMA behavior and Zener-viscoelasticity-based zigzag nonlinear corrections are implemented to guarantee the transverse stress continuity at the interfaces between layers and updating the relation between the describing parameters of the displacement field, and the stiffness and even mass matrices of the elements within each time step. For the first time, the phase-based rather than the mixture-based stresses are considered in tracing the phase transformations. The resulting time-dependent nonlinear integro-differential equations are solved by a special algorithm. Results confirm, for the first time, that the stress-strain hysteresis loops of the SMAs may shrink or even disappear in presence of the structural damping; so that, the belief that the phase-transformation-based damping and the structural damping directly add to each other, is quite wrong.

Magnetic Resonance Imaging as a Novel Method for Elucidating Sediment Burrow Structures and Functions.

Burrow structures produced by various benthic animals in sediments are important components of aquatic ecosystems, allowing the circulation of interstitial water via ingress of fresh bottom water into the burrows upon feeding and intraburrow migration. Although X-ray computed tomography has been used to visualize burrow structures, it could not reveal the structures in the soft mud in Lake Kasumigaura, where evaluation of the water-circulation effect of burrows is an important issue. Here, we describe the first attempt to use magnetic resonance (MR) imaging (MRI) to visualize intact burrow structures in the soft mud sediment cores collected from a eutrophic lake. Our MRI application clarified the dynamic distribution of burrows inhabited by chironomids in the soft mud that previous studies could not visualize. By examining the relationships between the degree of chloride ion depletion in deeper layers and the burrow density calculated from the MR images, we were able to consistently explain the water-circulation effect of burrows, suggesting the higher reliability of burrow density calculated from MR images. In addition, we were able to evaluate the activity of burrows, which is difficult to achieve in sediment core experiments. We observed a smaller water-circulation effect of burrows on ammonium ions than on chloride ions, suggesting the enhancement of ammonium production or release in burrow-rich sediments.