The Neural Network (NN) is applied to recognize basic PCB configurations using its magnetic near-field spectra and radiated far-field emission. The learning process is accomplished by using the computed spectra of the radiated field from PCBs having different configurations. The anomaly is detected through the monitoring of the spectra's amplitude frequency by injecting a voltage pulse at the PCB configuration. The trained NN is then applied to the identification of PCB layouts from radiated emission measurements. The trained NN can identify all of those PCB configurations from the magnetic near-field spectra and the radiated far-field EMI. Moreover, the calculated results of the NN are compared with the actual far-field measurements and other models for evaluation. Finally, the NN used for predicting far-field emission from their magnetic near-field measurement is proposed. Experiments show that the NN can predict the far-field spectra from the magnetic near-field spectra.

This letter presents a Monte-Carlo FDTD technique to determine the scattered field from a perfectly conducting fractal surface from which the useful information on the incoherent pattern tendency could be observed. A one-dimensional fractal surface was generated by the bandlimited Weierstrass function. In order to verify the numerical results by this technique, these results are compared with those of Kirchhoff approximations, which show a good match between them. To investigate the incoherent pattern tendency involved, the dependence of the fitting curve slope on the different D and is discussed for the bistatic and back scattering case, respectively.

The effect of a conductive sheet placed over a PCB with a microstrip line on electromagnetic noise shielding is investigated. As a typical conductive sheet, a copper sheet is used, and is not grounded. First, the input impedance of the microstrip line and the magnetic field when varying the distance between the PCB and the conductive sheet are measured, and the distance that does not affect the signal transmission is set at 8 mm. Second, the effect of the conductive sheet size on the magnetic field radiation is discussed by measurements and FDTD modeling, and the magnetic near-field distribution around the PCB is visualized by using the FDTD calculation. A conductive sheet whose width is larger than the PCB width should be effective for suppression of the magnetic near-field noise radiation just above a PCB.

Recently, a new approach was presented to determine the high-frequency response of on-chip passives and interconnects. The method solves the electric scalar and magnetic vector potentials in a prescribed gauge. The latter one is included by introducing an additional independent scalar field, whose field equation needs to be solved. This additional field is a mathematical aid that allows for the construction of a gauge-conditioned, regular matrix representation of the curl-curl operator acting on edge elements. This paper reports on the convergence properties of the new method and shows the first results of this new calculation scheme for VLSI-based structures at high frequencies. The high-frequent behavior of the substrate current, the skin effect and current crowding is evaluated.

In this paper, we investigate the electron-hole energy states and energy gap in three-dimensional (3D) InAs/GaAs quantum rings and dots with different shapes under external magnetic fields. Our realistic model formulation includes: (i) the effective mass Hamiltonian in non-parabolic approximation for electrons, (ii) the effective mass Hamiltonian in parabolic approximation for holes, (iii) the position- and energy-dependent quasi-particle effective mass approximation for electrons, (iv) the finite hard wall confinement potential, and (v) the Ben Daniel-Duke boundary conditions. To solve the 3D nonlinear problem without any fitting parameters, we have applied the nonlinear iterative method to obtain self-consistent solutions. Due to the penetration of applied magnetic fields into torus ring region, for ellipsoidal- and rectangular-shaped quantum rings we find nonperiodical oscillations of the energy gap between the lowest electron and hole states as a function of external magnetic fields. The nonperiodical oscillation is different from 1D periodical argument and strongly dependent on structure shape and size. The result is useful to study magneto-optical properties of the nanoscale quantum rings and dots.

This paper presents a framework for modeling and mixed-mode simulation of circuits/interconnects and electromagnetic (EM-) radiations. The proposed framework investigates the signal integrity in VLSI chips, packages and wiring boards at the GHz-band level, and verifies the electromagnetic interference (EMI) and the electromagnetic compatibility (EMC) of high-speed systems. In our framework, the frequency characteristics of interconnects and EM-radiations are extracted by the full-wave FDTD simulation. The macromodels of interconnects are synthesized as SPICE subcircuits, and the impulse responses of EM-radiations are stored in the database. Once the macromodels are synthesized, the circuit simulation with the consideration of EM-effects can be performed by using SPICE. The EM-field distributions can be also easily calculated by taking convolutions of pre-simulated EM impulse responses and the SPICE results.

The jaw movements can be measured by estimating the position and orientation of two small permanent magnets attached on the upper and lower jaws. It is a difficult problem to estimate the positions and orientations of the magnets from magnetic field because it is a typical inverse problem. The back propagation neural networks (BPNN) are applicable to solve this problem in short processing time. But its precision is not enough to apply to practical measurement. In the other hand, precise estimation is possible by using the nonlinear least-square (NLS) method. However, it takes long processing time for iterative calculation, and the solutions may be trapped in the local minima. In this paper, we propose a precise and fast measurement system which makes use of the estimation algorithm combining BPNN with NLS method. In this method, the BPNN performs an approximate estimation of magnet parameters in short processing time, and its result is used as the initial value of iterative calculation of NLS method. The cost function is solved by Gauss-Newton iteration algorithm. Precision, processing time and noise immunity were examined by computer simulations. These results shows the proposed system has satisfactory ability to be applied to practical measurement.

We fabricated the first Fe-coated fiber probe for magneto-optical applications. In order to improve the optical confinement capability, we used a double-layer structure, with a thin coating of Au. The double-layer structure consisted of 50-nm-thick Fe and 50-nm-thick Au. A probe-to-probe experiment confirmed that the fabricated fiber probe had an effective optical confinement capability for optical near-field measurement.

This paper presents the basic characteristics of a forced resonant type EMI dipole antenna for frequencies below 80 MHz in which two reactance elements are used for the impedance matching at the feed point. The input impedance of the short dipole less than half-wavelength is controlled by the properly determined loading position and the value of loading reactance. The integral equation for unknown current distribution is solved by Galerkin's method of moments with piecewise sinusoidal functions. The numerical results show that the small-sized EMI dipole antenna with lower antenna factors for frequencies below 80 MHz can be realized by the reactance loading. In case the proposed center driven small-sized EMI dipole antenna with 0.3λ length is loaded c=0.133λ from the center, the input impedance is matched at feed line with 50 Ω, and hence the antenna has lower factors in the frequency range of 30 to 80 MHz. Also the normalized site attenuation characteristics are presented for the forced resonant type EMI dipole antenna.

Co-containing ferrite thin-film media deposited by a reactive-ECR-sputtering at a low substrate temperature of 150 degree Celsius were oxidized by ECR plasma. The magnetic properties and recording characteristics of the media were improved by the oxidation with maintaining a smooth surface. The media showed high D50 of 203 kFRPI in MIG head recording and reproduction. The Co-containing ferrite thin-film is feasible to be used as a protective overcoat layer.

As technology moves to 600-1000 Gb/sq-in areal densities and deep sub-10 nm head-disk spacing, it is of crucial importance to prevent both the conventionally defined thermal decay and the tribologically induced decay of recorded magnetic signal. This paper reports a novel method for recording and visualizing the signature of the potential tribological decay. The details of the methodology, its working principles, and typical results obtained are presented in this work. The method is based on the introduction of a type of visualizing disks which use a layer of magneto-optical material with low Curie temperature to replace the magnetic layer used in the conventional magnetic media. The method and corresponding setup were used successfully in the visualization of potential decay caused by slider-particle-disk contact, slider-disk contact during track seeking operations, and slider-disk impact during loading and unloading operations.

Patterned magnetic media are promising to be the next generation recording media for computer hard disk drives to go beyond the density of 100 Gb/in2. A micromagnetic simulation model is set up to study the magnetic property as well as the recording process in patterned media. The patterned medium studied in this paper is an array of pillar magnetic particles with a perpendicular anisotropy. A pole record head as well as a thin film head are utilized in the simulated recording process. The diameter of the magnetic pillars is chosen as 20 nm, the bit length takes the values of 30 nm, 40 nm and 50 nm, with respect to an ideal areal density of 258 Gb/in2, 459 Gb/in2 and 717 Gb/in2. The magnetic signal and noise recorded in a series of patterned media are analyzed at different recording densities with the two types of record heads.

The interaction between slider, lubricant and disk surface is becoming the most crucial robustness concern of advanced data storage systems. This paper reports comparative studies among various techniques for the measurement of head-disk spacing. It is noticed that the triple harmonic method gives a reading much closer to the reading of the head-disk spacing obtained optically at on-track center case, comparing with the PW50 method. Specially prepared disks with different carbon overcoat thickness (6.5 nm, 11 nm, 16 nm and 22 nm) were also used to study the reliability and repeatability of the triple harmonic method.

In recent years, perpendicular magnetic recording have progressed rapidly. It will not be long before perpendicular magnetic recording is put into practical use. However there have been few tools contributing to the optimum design of perpendicular magnetic recording media and heads except computer simulations. The authors have introduced a simple method based on the concept of self-consistent magnetization to analytically predict a transition parameter in terms of parameters of recording media and writing heads. Moreover we have discussed the origin of media noise by using a time-domain analysis of readout voltage and Voronoi cell model analysis. In this paper, main parameters to realize high bit density recording over 100 Gbit/inch2 is discussed first through these methods, and then the current status, the future problems and the prospects in perpendicular magnetic recording technology are described.

A simplified model is set up to study the high frequency response in a thin film head, where two pieces of Fe-Al-N films are placed parallel to each other with opposite alternating external magnetic field applied. In this model, the frequency response of magnetic clusters is calculated by a micromagnetic model based on the Landau-Lifshitz-Gilbert equations, and the initial permeability of mesoscopic Fe-Al-N thin films is analyzed in a wide frequency region from 10 to 5000 MHz. The model of a soft magnetic thin film is built up on the ripple structure of the anisotropy field of magnetic clusters. The magnetization interaction between the two Fe-Al-N films is carefully computed to find its effect on the frequency response. The frequency response in a single mesoscopic Fe-Al-N thin film is carefully studied in advance.

Metal particulate tape is one of the most advanced tape media to offer excellent performance at high recording densities. An accurate micromagnetic model of the metal particulate tape has been developed to analyze the magnetic properties of MP tapes. Both particle size distributions and orientation distribution are included in the model, and the magnetostatic interactions among particles are accurately calculated with the shape of ellipsoids. A partial mean field approximation applied in the calculation is proved to be effective by M-H loop analysis.

Write linear density limit is defined to analyze the magnetic recording process in computer hard disk drives at extremely high recording densities. The digital data with pseudo random sequences are recorded numerically in longitudinal media at different densities by a micromagnetic simulation model. A thin film write head and an ideal GMR read head are utilized in the record and read-back process, respectively. A novel method has been utilized to study the write linear density limit: the simulated read back voltage and the respected linear superposed pulses are compared to find the distortion in the record process. When a severe distortion shows up, the corresponding linear density is considered as the write linear density limit. By the novel method, the write linear density limit is analyzed with different parameters of the recording media.

A novel technique for automatic segmentation of a brain region in single channel MR images for visualization and analysis of a human brain is presented. The method generates a volume of brain masks by automatic thresholding using a dual curve fitting technique and by 3D morphological operations. The dual curve fitting can reduce an error in curve fitting to the histogram of MR images. The 3D morphological operations, including erosion, labeling of connected-components, max-feature operation, and dilation, are applied to the cubic volume of masks reconstructed from the thresholded brain masks. This method can automatically segment a brain region in any displayed type of sequences, including extreme slices, of SPGR, T1-, T2-, and PD-weighted MR image data sets which are not required to contain the entire brain. In the experiments, the algorithm was applied to 20 sets of MR images and showed over 0.97 of similarity index in comparison with manual drawing.

The effect of a nonmagnetic hcp-underlayer on the epitaxial growth of CoCr19Pt10 magnetic layers on substrates of Al2O3(0001) single-crystal has been investigated. Thin films of (0001)-oriented single-crystal CoCr19Pt10 were obtained by employing non-magnetic underlayers of CoCr25Ru25 and CoCr25Ru25/Ti, while thin films of polycrystalline CoCr19Pt10 were grown after the deposition of underlayers of TiCr10 and CoCr40. The growth of thin film CoCr19Pt10 on a Ti(0001) underlayer was interpreted as quasi-hetero-epitaxial where the continuity of the lattice across the interface is disturbed while the overall crystallographic relationship between the two layers is maintained. A thin film of epitaxially grown CoCr19Pt10 has a compositional variation of a few percent across the film plane in terms of elements that forms the alloy.

The transient phenomenon of electromagnetic waves caused by a time dependent resistive screen in a waveguide is treated by using Wiener-Hopf technique. A boundary-value problem is formulated to describe the phenomenon, in which the resistivity of screen varies from infinite to zero in dependence on time. Application of the Fourier transformation with respect to time derives a Wiener-Hopf equation, which is solved by a commonly known decomposition procedure. The transient field is derived from the solution of the equation in terms of the Fourier inverse transform. By using the incomplete Lipschitz-Hankel integral for the computation of the field, numerical examples are given and the transient phenomenon is discussed.