Core Shape Research Articles

Integrated Magnetic Circuits for Differential-mode and Common-mode Chokes of EMI Filters


 In this paper, two magnetic circuits to integrate common-mode (CM) and differential-mode (DM) chokes of an electromagnetic interference (EMI) filter are proposed. The DM and CM chokes are integrated by using UIU and EI ferrite core shapes. To evaluate the EMI reduction performances of proposed approaches, the conducted EMI reduction performances of proposed integrated DM and CM chokes are compared with the conventional CM choke and traditional separated DM and CM chokes. From the experimental results, it ensures the advantages of the use of proposed approaches. Although some magnetic parts are eliminated by proposed approaches, the amount of DM and CM EMI attenuation rate is comparable to the case of traditional separated DM and CM chokes, except the highest peak is located at different frequencies.

The effect of side slope and clay core shape on the stability of embankment dam: Southern Ethiopia

In a dam construction, the primary concern is the economy and stability of the dam construction, in parallel with the benefit gained from it. The Gidabo rock fill dam has nearly flatter (2H:1V) side slope with 22 m dam height from river bed level, which consume high fill material relative to this height and dam type. In this study, the effect of clay core shape and side slopes on the stability of embankment dam is analyzed and the minimum earthwork consumption with stable dam safety is identified. The identified best side slope and shape of clay core has checked for all loading condition with numerical modeling software called Geo-Studio 2012. Based on computation the factor of safety of 1.514 and 1.611 for upstream and downstream at end of construction, 1.504 for steady state condition, 1.316 for sudden drawdown and flux through the dam has been found to be 1.95 × 10−7 m3/s/m. The horizontal and vertical deformation of the dam at normal pool level is 0.023 m and 0.192 m, respectively, which are all within the allowable limit. Hence, the selected clay core shape and side slope dam fulfill all design criterion and reduce the consumption of shell fill material.

Systematical Approach for Vent Design of Core Out-Gassing Through Development of an Inventive Evaluation Device

Casting defects caused by the core gas evolution impair the performance of a machine. The estimation of core gas evolution and core out-gassing are necessary for thin-wall high-pressure castings with complicated actual size core systems. The development of our patented device for core out-gassing made possible a systematical approach for the vent design of core out-gassing in the design stage of the core shape and the mold concepts of casting, such as engine parts with complicated core systems. Experimental procedures and analytical reviews on the relative performance evaluation of suction routes of core gas were attempted with aluminum thin-wall cylinder head casting. Also, two different distributions of particle sizes of core sand were evaluated in order to review effects of fine particle of core sand on core out-gassing. The device developed for core out-gassing in this study was composed of a chamber, a vacuum pump, pressure sensors, and a data logger.

Deciphering the Multifarious Charge-Transport Behaviour of Crystalline Propeller-Shaped Triphenylamine Analogues.

A collection of para-substituted propeller-shaped triphenylamine (TPA) derivatives have been computationally investigated for charge-transport characteristics exhibited by the derivatives by using the Marcus-Hush formalism. The various substituents chosen herein, with features that range from electron withdrawing to electron donating in nature, play a key role in defining the reorganisation energy and electronic coupling properties of the TPA derivatives. The TPA moiety is expected to possess weak electronic coupling on the basis of poor orbital overlap upon aggregation, owing to the restriction imposed by the propeller shape of the TPA core. However, the substituent groups attached to the TPA core can significantly dictate the crystal-packing motif of the TPA derivatives, wherein the variety of noncovalent intermolecular interactions subsequently generated drive the packing arrangement and influence electronic coupling between the neighbouring orbitals. Intermolecular interactions in the crystalline architecture of TPA derivatives were probed by using Hirshfeld and quantum theory of atoms-in-molecules techniques. Furthermore, symmetry-adapted perturbation theory analysis of the TPA analogues has revealed that a periodic arrangement of energetically stable dimers with significant electronic coupling is essential to contribute high charge-carrier mobility to the overall crystal.

Morphological transformation of gold nanoparticles on graphene oxide: effects of capping ligands and surface interactions

This article presents the influence of capping ligand and surface interaction types on the coarsening or reshaping behavior of surface-immobilized gold nanoparticles with different core size and shape. The morphological transformation of gold nanoparticles and nanorods on graphene oxide upon heating at temperatures ranging from 50 to 200 °C was investigated. The aggregation and coarsening behaviors of spherical nanoparticles on graphene oxide were slightly affected by the core size of nanoparticles (~ 1, 3, and 10 nm). The comparison of two different surface ligands revealed that glutathione ligands provide much better protection than cetyltrimethylammonium bromide ligands against the morphological transformation of nanoparticles. In addition, the evaluation of surface binding interactions indicated that the attachment of nanoparticles and nanorods onto graphene oxide with additional thiol functional groups could improve the immobilization of particles and therefore decelerate coarsening and reshaping of nanoparticle and nanorods.

NUMERICAL OPTIMIZATION OF SANDWICH COMPOSITE STRUCTURE UNDER FLEXURAL LOAD

The structures of a sandwich composite have been utilized in the aerospace industry andengineering applications. Prediction of a theoretical composite construction's flexuralproperties is important for efficient composite products design. In this investigation, fourdifferent core shapes were used in the fabrication of the sandwich frames with constantvolume of sandwich composite structure in each case; these are hexagonal, rectangular,triangular and circular. The effect of core stiffeners number was studied to finding the beststiffeners number which gives the highest properties in strength using the finite elementanalysis.The material of the each face sheet is consisting from epoxy with four layers of a wovenfiberglass laminate construction, and the core stiffener material consists from epoxy matrixwith carbon fiber, the fiber volume fraction was 60% for both skins and core composites.The analysis of the three point bending load with a value of (10 kN) conducted byconstructing a finite element model, explained that the best shape of core was rectangularwhich give less deflection value of (11.939 mm) from the other shapes, for the sameproperties of material and constant core volume in each case. Also, it was determined theoptimum stiffeners number, for the rectangular core, was five stiffeners in longitudinaldirection and twelve stiffeners in transverse direction, gives strengthen structure.

Onion-Like Carbon Nanostructures: An Overview of Bio-Applications

This article presents a brief review of the knowledge concerning onion-like carbons (OLCs). These nanostructures are some of the most fascinating carbon forms due to their unusual structure and physico-chemical properties. Generally, OLCs consist of a hollowspherical fullerene core surrounded by concentric graphitic layers with increasing diameter. Nevertheless, they can have different size, shape and type of core, which determine their physicochemical properties. In this article, we review the most important literature reports in this area and briefly describe these nanostructures, their physical and chemical properties and their potential uses with a focus on biomedicine.

Новые данные по мезолиту Южного Приангарья (по материалам местонахождения Приют Сукачева 2)

The results of archaeological works carried out in 2017 at the Priyut Sukacheva 2 site (Irkutsk) and analysis of the Mesolithic stone industry are presented. During the excavation, we uncovered the Pleistocene and Holocene deposits and identified two cultural layers. Mixed and poorly informative materials were found in the 1th layer, which is dated, in accordance with the ceramics, to a wide period from Neolithic to the Middle Ages. The most interesting finds of this layer are a flint zoomorphic figurine and a sandstone bait fish. The most representative is the collection of the 2nd layer. Three fireplaces made of pebbles were found here, which were severely destroyed because of cryogenic processes at the end of the Early – beginning of the Middle Holocene. The collection includes almost 6 thousand finds, among which were noted: debitage, cores and precors, end-scrapers (the most numerous category), incisors, borers, points, combined and notched tools, abrasive tools, preforms of tools, a knife, a side-scraper, pebbles and pieces of rock. The collection also consist of a few faunal remains (Equus ferus, Cervidae and ungulates). According to the specificity of lithic assemblage and the presence of large fireplaces, we can assume that there was a short-term settlement of hunter-gatherers. Here, the primary stone knapping was carried out, that indicated by the finds of cores, precors, flakes, and pieces of rock. Along with this, intensive economic activities were carried out, which was probably associated with various works on skin dressing, processing bone and wood. Despite of the lack of radiocarbon dates, the lithic assemblage of the 2nd layer is sufficiently expressive for a detailed comparison with materials from other sites. As a result of the collection analysis, the greatest similarity with the Late Mesolithic complexes of the Lisikha site, located on the opposite bank of Angara river, was found. Both sites have a similarity in the preferences of the inhabitants in the choice of raw materials (mudstone), the shape of cores and tools, and the stratigraphic position of the archaeological materials. Taking into account all the data, the age of complexes from the 2nd layer at the Priyut Sukacheva 2 site should be determined by the Final Mesolithic (~9.5–8.5 ka cal BP). The results of stratigraphic analysis do not contradict these conclusions.

Molecular-Level "Observations" of the Behavior of Gold Nanoparticles in Aqueous Solution and Interacting with a Lipid Bilayer Membrane.

We use coarse-grained molecular dynamics simulations to "observe" details of interactions between ligand-covered gold nanoparticles and a lipid bilayer model membrane. In molecular dynamics simulations, one puts the individual atoms and groups of atoms of the physical system to be "observed" into a simulation box, specifies the forms of the potential energies of interactions between them (ultimately quantum based), and lets them individually move classically according to Newton's equations of motion, based on the forces arising from the assumed potential energy forms. The atoms that are chemically bonded to each other stay chemically bonded, following known potentials (force fields) that permit internal degrees of freedom (internal rotation, torsion, vibrations), and the interactions between nonbonded atoms are simplified to Lennard-Jones forms (in our case) and coulombic (where electrical charges are present) in which the parameters are previously optimized to reproduce thermodynamic properties or are based on quantum electronic calculations. The system is started out at a reasonable set of coordinates for all atoms or groups of atoms, and then permitted to develop according to the equations of motion, one small step (usually 10 fs time step) at a time, for millions of steps until the system is at a quasi-equilibrium (usually reached after hundreds of nanoseconds). We then let the system play out its motions further for many nanoseconds to observe the behavior, periodically taking snapshots (saving all positions and energies), and post-processing the snapshots to obtain various average descriptions of the system. Alkanethiols of various lengths serve as examples of hydrophobic ligands and methyl-terminated PEG with various numbers of monomer units serve as examples of hydrophilic ligands. Spherical gold particles of various diameters as well as gold nanorods form the core to which ligands are attached. The nanoparticles are characterized at the molecular level, especially the distributions of ligand configurations and their dependence on ligand length, and surface coverage. Self-assembly of the bilayer from an isotropic solution and observation of membrane properties that correspond well to experimental values validate the simulations. The mechanism of permeation of a gold NP coated with either a hydrophobic or a hydrophilic ligand, and its dependence on surface coverage, ligand length, core diameter, and core shape, is investigated. Lipid response such as lipid flip-flops, lipid extraction, and changes in order parameter of the lipid tails are examined in detail. The mechanism of permeation of a PEGylated nanorod is shown to occur by tilting, lying down, rotating, and straightening up. The nature of the information provided by molecular dynamics simulations permits understanding of the detailed behavior of gold nanoparticles interacting with lipid membranes which in turn helps to understand why some known systems work better than others and aids the design of new particles and improvement of methods for preparing existing ones.

Reduction of Inverter Carrier Harmonic Losses in Interior Permanent Magnet Synchronous Motors by Optimizing Rotor and Stator Shapes

In this paper, we investigate rotor and stator designs of interior permanent synchronous motors for variable speed/load applications to reduce the carrier harmonic losses caused by pulsewidth modulated inverters. The rotor core and magnet shapes are determined by automatic optimization methods with electromagnetic field analysis, which considers the inverter carrier. Appropriate stator-winding configurations are also investigated by this analysis. It is clarified that the total carrier harmonic loss can be reduced by more than 20% by optimizing both the stator and rotor shapes, whereas the other important characteristics are not deteriorated. The mechanism of carrier loss reduction is also clarified.

Assessment of the inflatable core assisted paper bottle moulding process

Eco-friendly products have gained importance in recent years. The paper bottle is a sustainable packaging solution for carbonated beverages. The moulding process is a two-stage process. At first, pulp is poured in the forming mould and fibers are formed in the desired shape. Wet bottle is then transferred to the drying mould to remove bound water. The drying process makes use of an inflatable core, which not only prevents the shrinkage of fibers but also helps in attaining good fiber compaction. Preliminary investigations reported uneven fiber compaction in changing curvatures and sharp corners. A cause of uneven thickness distribution in the geometry is uneven compaction pressure during core expansion. A FEM approach is developed to predict the occurrence of non-conformities in the bottle. Hyperelastic core material is modelled using Mooney-Rivlin material model from the elastic strain density function. The model can be used to optimize the core shape, thus developing a robust tooling solution.

Transient Core-Loss Simulation for Ferrites With Nonuniform Field in SPICE

A methodology to develop a subcircuit model for core loss simulation in LTspice is presented. The subcircuit implements the dynamic core loss model used in the transient solver of finite-element analysis (FEA) in order to provide equivalent results in the time domain for ferrite materials. The wipe-out rule is applied in the simulation so that the core loss during the transient behavior can be predicted. A field factor is derived from an effective flux density for a nonuniform flux distribution to simplify the relationship between the current and the field for arbitrary magnetic core shapes. The interface of the subcircuit is capable of being integrated to any power stage simulations. Simulation results of core loss equivalent to the FEA on an exemplary plate-core inductor are obtained from the subcircuit that significantly reduces computational cost.

Highly Demagnetization Performance IPMSM Under Hot Environments

This paper examines how changing the magnetic orientation of permanent magnets in concentrated winding interior permanent magnet synchronous motors (IPMSMs) affects their demagnetization resistance. We evaluated a prototype for demagnetization at 180 °C that consists of a 130° V-shaped rotor core in which parallelogram magnets with oblique orientation are arranged and confirmed by finite element analysis where the demagnetization resistance increases as magnetic field orientation angle $\alpha $ becomes larger. For demagnetization evaluation of the prototype, it is easier to change the rotor core shape of a two-pole test rotor of a multipole IPMSM than a multipole rotor, and the demagnetization evaluation is performed using a small number of magnets.

Analysis of Torque Characteristics according to Non-uniform Air Gaps of Coaxial Magnetic Gear

Recently, studies on magnetic gears have been actively conducted. Magnetic gears can replace mechanical gears as they can perform noncontact power transfer, thereby minimizing loss and damage from friction. A magnetic gear has two rotors with different numbers of poles because of its structural characteristics. For a rotor with a relatively lower number of poles, large torque ripples occur owing to the increase in the permeance variation within the air gaps. Other electric equipment studies conducted thus far have primarily changed the shape of iron core to reduce torque ripples. However, since the magnetic gear has two air gaps, it is necessary to identify the relationship between the two gaps and the ripple before changing the shape of the iron core. In this paper, factors that affect torque ripple are classified and analyzed by examining the magnetic flux density of two air gaps, to propose an air gap structure that benefits the design of magnetic gears.

Hollow Core Slabs on Winkler Foundation

This research dealt with the linear elastic behavior of hollow core slabs resting on a linear Winkler type foundation. A finite difference method was used to model the slabs as wide beams and the foundation as elastic springs. The finite element method was also used to model the problem using ABAQUS 6.10 software program. A comparison between the method proposed in this paper and methods from previous studies was made to check the accuracy of the solutions. Several important parameters were incorporated in the analysis, viz. the hollow core size and shape, subgrade reaction and slab depth, to trace their effects on deflections, bending moments and shear forces. A computer program coded in Fortran was developed for the analysis of hollow core slabs on an elastic foundation. It was found that the maximum difference in deflection between the present study and the exact solution was 3% for the finite difference and 7% for the finite element method.

The use of iron oxide magnetic nanospheres and nanocubes for targeted doxorubicin delivery into 4t1 mouse breast carcinoma cells

Magnetic nanoparticles (MNP) are attracting increasing attention as promising materials for the treatment and diagnosis of cancer. The aim of this work was to explore the effect of the magnetic core shape of iron oxide nanoparticles (NP) on the efficiency of doxorubicin delivery into 4T1 cells. Nanospheres (NS) and nanocubes (NC) were synthesized by thermal decomposition of iron (III) oleate. This method of synthesis enables control over the NP shape and size. The NP were hydrophilized using Pluronic F-127. The obtained particles were doped with doxorubicin in a sodium phosphate buffer. The weight fractions of doxorubicin in the NS and NC were 15.22% and 15.44%, respectively. The IC50 of free doxorubicin was 1 μM. The IC50 of doxorubicin-loaded NS and NC were 6.4 μM and 5.5 μM, respectively. Unloaded NP did not exhibit any toxicity towards the cells at a studied range of concentrations between 1.77 mg/l and 227.2 mg/l. Free doxorubicin demonstrated more vigorous accumulation dynamics in 4T1 cells with a tendency to localize in the cell nucleus, whereas doxorubicin loaded onto iron oxide NP was mainly accumulated in the vesicles surrounding the nucleus and was able to enter it only after being incubated with the cells for 2 h. We conclude that doxorubicin loaded onto cubic-shaped NP is delivered into the cell nucleus a little bit more efficiently at early incubation stages in comparison with nanospheres, but the difference is insignificant.

Magnetic Analysis of Copper Coil Power Pad with Ferrite Core for Wireless Charging Application

Wireless charging can automate the charging of electrical devices, very quickly connected with IoT based smart systems. The efficiency of wireless charging collectively depends on the design of the power pad, the frequency level of power transfer, the distance between the transmitter and receiver, alignment between the coils. Coils design comprehend the shape of the coil, material of the coil used, the thickness of the wire used and core shape and material used in the core. The manuscript compares the power pad coil shapes, with the introduction of ferrite material core across the coils to design an extremely efficient power pad for the wireless charging of electric vehicle. A 3D finite element method was used for analysis, due to the unconventional distribution of the flux. Only three types of coils, D, DD, and DDQ, are taken for analysis of magnetic core introduction. The comparison is made based on simulation results, magnetic flux pattern as well as data imported from the results. Ansys 3D Maxwell simulation software is used to simulate the magnetic pattern of the power pad coils. Finally, the results show the DD type coil shows the best magnetic fields and the maximum coupling coefficient with the maximum misalignment tolerance and the ferrite core across the coils have aligned the magnetic flux pattern and slightly improved the coupling coefficient.

A Procedure for the Extraction of Intrinsic AC Conductivity and Dielectric Constant of N87 Mn–Zn Ferrite Samples Based on Impedance Measurements and Equivalent Electrical Circuit Modeling

The nature of losses in ferrites has not been fully revealed yet. To achieve means for further investigation of ferrite core loss due to electric (E) field, we investigated the response of middle and side legs, cut from commercially available PQ core halves, to an applied E-field, by injecting a sine wave current in the samples. Using conventional laboratory instruments, we did impedance measurements in a wide frequency range (133 Hz–50 MHz) at temperatures that are typical for power electronics (25, 85, 100, and 120 °C). In this paper, we discuss a procedure for the extraction of intrinsic ac conductivity and dielectric constant of ferrites through an equivalent electrical circuit model based on the measured impedances. The examined material is of grade N87. The measurements show a clear influence of the investigated shapes. The results obtained start to deviate from “true” electrical properties at about 1 MHz. It appeared also that the inspected ferrites exhibit different conductivities and dielectric constants depending on the core of origin. It is obvious then that core shape, size, and production batch all have an impact on the core losses, which appear to be influenced by the E-field even at frequencies below 1 MHz.

Influences of asymmetrical geometric structures on the birefringence of index-guiding photonic crystal fiber

We have numerically investigated the influences of asymmetrical geometric structures on the birefringence of the index-guiding photonic crystal fiber (IG-PCF), by the finite element method. The structure of a reported highly birefringent (HB) PCF with artificial defect in the core is modified to destruct the symmetry. Our proposed structural modifications include elliptical air hole cladding, squeezing lattice of air holes, rotational elliptical air holes, and horizontally shifted air holes, in the cladding. It is found that the birefringence is sensitive to the modifications in different cases due to the different mechanisms. For 1550 nm wavelength, the optimized birefringence can be obtained to be 0.0328 by the elliptical air holes with the major semi-axis in the direction of the long side of the rectangular core region. Furthermore, for the HB-PCF by the asymmetric core shape, the structural factor restricting the further increase of birefringence is that continuous increase of asymmetry leading to the multi-core transmission. It seems to be that This work is not only a proposing of the optimal design of HB-PCF, but also a reference of founding the essence of geometric birefringence.

Characterization of compressive behavior of PVC foam infilled composite sandwich panels with different corrugated core shapes

Increasing the development in industrial technology and need for energy absorption, lightweight and cost effective composite materials such as composite sandwich panels have been in the center of attention. In this paper energy absorption properties of proposed composite sandwich panels with different corrugated core geometries under quasi static out of plane loading conditions is experimentally investigated. Three different corrugated shapes, i.e. rectangular, trapezoidal and triangular fabricated with the same thickness are used. The specimens were subjected to three different quasi-static compression loading condition i.e. concentrated, linear and planar. The effect of the number of unit cells and corrugated core geometries in determining the overall deformation and local collapse behavior of the panels also investigated. Based on the comparative results, it is found that three unit cell rectangular corrugated geometry possessed the best performance than other types of corrugated core geometries. Moreover, through visual observation the damage mechanisms under loading conditions and subsequent failure modes are inspected. Plastic buckling of cell walls and foam densification identified as the initial failure modes and by continuing the loading, fiber breakage, localized delamination as well as debonding between the skins and the core were the main damage mechanisms in these corrugated systems.