Magnetic core

About: Magnetic core is a research topic. Over the lifetime, 30011 publications have been published within this topic receiving 155247 citations.

Combined optical and magnetic transducer

Abstract: A combined optical and magnetic transducer for sensing both optical and magnetic properties of an article, for example, a piece of paper currency or other document having both visible and magnetic markings to be tested or read, an information-bearing medium such as a data-recording tape to be read, or the like. The transducer comprises a magnetic-sensing head having a transparent gap separating the poles of the magnetic core of the head, a photoelectric element being disposed in the head in alignment with the gap. Outside the head, one side of the article contacts or is in close proximity to the poles at the gap, and the article is illuminated by a light source, so that both magnetic properties and optical properties of the article may be detected simultaneously during relative movement of the article and the transducer.

Effect of surface modification on magnetization of iron oxide nanoparticle colloids

Abstract: Magnetic iron oxide nanoparticles have numerous applications in the biomedical field, some more mature, such as contrast agents in magnetic resonance imaging (MRI), and some emerging, such as heating agents in hyperthermia for cancer therapy. In all of these applications, the magnetic particles are coated with surfactants and polymers to enhance biocompatibility, prevent agglomeration, and add functionality. However, the coatings may interact with the surface atoms of the magnetic core and form a magnetically disordered layer, reducing the total amount of the magnetic phase, which is the key parameter in many applications. In the current study, amine and carboxyl functionalized and bare iron oxide nanoparticles, all suspended in water, were purchased and characterized. The presence of the coatings in commercial samples was verified with X-ray photoelectron spectroscopy (XPS). The class of iron oxide (magnetite) was verified via Raman spectroscopy and X-ray diffraction. In addition to these, in-house prepared iron oxide nanoparticles coated with oleic acid and suspended in heptane and hexane were also investigated. The saturation magnetization obtained from vibrating sample magnetometry (VSM) measurements was used to determine the effective concentration of magnetic phase in all samples. The Tiron chelation test was then utilized to check the real concentration of the iron oxide in the suspension. The difference between the concentration results from VSM and the Tiron test confirmed the reduction of magnetic phase of magnetic core in the presence of coatings and different suspension media. For the biocompatible coatings, the largest reduction was experienced by amine particles, where the ratio of the effective weight of magnetic phase reported to the real weight was 0.5. Carboxyl-coated samples experienced smaller reduction with a ratio of 0.64. Uncoated sample also exhibits a reduction with a ratio of 0.6. Oleic acid covered samples show a solvent-depended reduction with a ratio of 0.5 in heptane and 0.4 in hexane. The corresponding effective thickness of the nonmagnetic layer between magnetic core and surface coating was calculated by fitting experimentally measured magnetization to the modified Langevin equation.

Interleaved DC to DC flyback converters with reduced current and voltage stresses

Abstract: Interleaved flyback DC to DC converters are provided comprising a first and a second switching transistors controllable with 180° phase shift and a first and a second flyback transformers. A primary winding of each transformer is coupled in a series circuit with the corresponding switching transistor. A secondary winding of the first transformer is coupled with the secondary winding of the second transformer via a first catch diode and both said secondary windings are coupled to an output filter capacitor via a second and a third catch diode, correspondingly. When discharging to the output filter capacitor, the transformers interlock each other. By interlocking, non-pulsating output current is generated and voltage across switching transistors is reduced. A secondary quasi-resonant snubber network relieves voltage spikes across the switching transistors. A common magnetic core of the transformers cuts the cost and the size of the interleaved flyback converters.

rf superconducting quantum interference device metamaterials

Abstract: A rf superconducting quantum interference device (SQUID) array in an alternating magnetic field is investigated with respect to its effective magnetic permeability, within the effective medium approximation. This system acts as an inherently nonlinear magnetic metamaterial, leading to negative magnetic response, and thus negative permeability above the resonance frequency of the individual SQUIDs. Moreover, the permeability exhibits oscillatory behavior at low field intensities, allowing its tuning by a slight change of the intensity of the applied field.

Magnetic structure and magnetic head using the same

Abstract: A magnetic structure and a magnetic head capable of reducing the size thereof and raising the degree of integration is disclosed which has a structure including a substrate having a plurality of ridge-like projections each having slant side-surfaces; the substrate having thereon: a first conductive passage consisting of a plurality of parallel and conductive passages each of which is formed on opposing slant surfaces of adjacent projections and on the bottom surface between the slant surfaces; a first insulating layer stacked on the first conductive passage and the substrate; a magnetic core made of magnetic material enclosed in a groove-shape recess formed by the adjacent projections and the bottom surface; a second insulating layer stacked on the magnetic core; and a second conductive passage formed on the second insulating layer to sequentially connect ends of the first conductive passage to form a helical coil, wherein the magnetic core is separated by the projection so that a plurality of coils are integrally formed on the same substrate.