It is known that amorphous continuous media such as TbFeCo have extremely low noise characteristics because of the structure of the continuous grainless medium. There is great interest in the use of amorphous media in magnetic recording. This study investigated the recording characteristics of the amorphous continuous medium by computer simulation using the Landau-Lifshitz-Gilbert equation. It was shown that the transition of the continuous medium is very sharp and the noise level very low. It was also shown that the recorded magnetization patterns of the continuous medium are distinct at the high recording density of 380 Gbit/inch2. We concluded that the continuous medium has great potential for use in ultra-high density recording.

A Co/Pd multilayer film with perpendicular coercivity of 2.2 kOe and remanence ratio (SQ) of unity was prepared by electron beam evaporation in vacuum. In the MFM image of signal patterns of 4 kFRPI recorded using a ring-type MIG head, many reversed domains were observed. However, when the film was magnetized along the film normal direction using an electromagnet (H = -13 kOe), only few reversed magnetic domains were observed, which was consistent with SQ = 1. Therefore, the reversed domains in the signal patterns were induced in the recording process. dc erasing was also studied with the magnetic field inclined to the film normal. The domain structures were almost the same when the perpendicular component of the field was kept constant while the in-plane component was varied, implying that the in-plane field component did not contribute to the formation of the reversed domains. It was found that reversed magnetic domains were easily induced even by a weak reversing magnetic field applied along the film normal. Hence, although the possibility of an insufficient recording head field was not excluded, it seemed more likely that the reversed magnetic domains in the signal patterns were caused by some erasing effect of the ring-type MIG head. For a Co/Pd multilayer medium with a negative nucleation field in the perpendicular M-H loop, a stronger reversing field was needed to induce the reversed magnetic domains. No reversed magnetic domains were observed in the MFM image for signal patterns of 4 kFRPI in this medium, indicating that a negative nucleation field was effective to suppress the formation of reversed magnetic domains.

The origins of baseline shift were discussed considering the measured off-track properties using a wide write head with track widths of 97 µm and a narrow read head with track widths of 2.7 µm. The baseline shift increased when the read head was moved close to the track edge. Beyond the track edge, baseline shift decreased to negative values. The impulse response curve of the MR head to the perpendicular magnetization was estimated from the readback waves of the MIG head and the MR head. The response curve depended on the recorded track width. When the recorded track was narrow, the undershoot of the response curve was smaller than that of the head field based on the 2D double-gap ring head model with infinite track width. This small undershoot induces sensitivity of the DC-component of the recorded magnetization and causes the baseline shift. To calculate the readback waves of the MR head for single-layer perpendicular recording media with narrow-track recording, the effect from stray field at the recorded track edge must be included in the impulse response curve of read head.

The medium noise of single-layer perpendicular recording media is known to be suppressed by reducing the magnetic domain size and achieving a higher squareness ratio (Mr/Ms = SQ) in the perpendicular M-H loop. The media with smaller domain sizes exhibit a small slope at Hc in the M-H loop due to exchange de-coupling between adjacent grains, which requires a sharp head field to acquire high recording performances. Reduction of the medium thickness would be effective for recording as only a sharp head field near the head surface could be used. Thus, the effects of reduced recording layer thickness in single-layer perpendicular recording media on read/write performances were investigated using Co/Pd multilayer media with a small loop slope having thickness, δ, of 46, 22 and 10 nm, and with a steeper loop slope having δ of 40 and 10 nm. It was found that the recording performance on small loop slope media could be improved in terms of signal level by reducing the recording layer thickness, which indicated that the recording on the media was sensitive to the recording head field. The results in the simulation analysis were similar to those obtained experimentally, indicating that the change in recording layer thickness could be mainly regarded as that in the head-medium spacing. Thinner media with steeper loop slopes could acquire a narrower dipulse width. The recording resolution of the present media, however, was determined under the influence of the domain structure and the size. Finally, for media with small loop slopes, the same SNR of 38 dB at 100 kFRPI was obtained for thicknesses of 22 and 10 nm, which was larger than that for a thick medium of 46 nm thickness by 8 dB. For both the steep loop slope media, the obtained SNR was 35 dB at 100 kFRPI.

Ferromagnetic Co77Cr20Ta3 layers were deposited on a Pt seed layer by a facing targets sputtering apparatus. The Co-Cr-Ta and Pt crystallites revealed better c-axis orientation at a substrate temperature Ts above 200C. Relatively high perpendicular coercivity Hc⊥ of 2.5 kOe was obtained for the bilayered film with a Co-Cr-Ta layer thickness, δCo, of 50 nm deposited at Ts of 250C. Although the Co-Cr-Ta/Pt medium with δCo of 100 nm exhibited lower recording density than a Co-Cr-Ta/Cr longitudinal one, its noise level became small at the high-density recording range. Measurement of the anomalous Hall voltage clarified that the bilayered film with δCo as small as 30 nm revealed larger perpendicular magnetization than the single layer. The Pt seed layer is effective for depositing thin ferromagnetic Co-Cr-Ta layers below 100 nm in thickness.

Numerical modeling of realistic engineering problems using the FDTD technique often requires smaller cell size, higher simulation accuracy and less computation resources. In this paper, we describe a high performance three-dimensional FDTD algorithm by using non-uniform mesh that allows flexible cell size to improve the accuracy of modeling, and computation resource also can be reduced greatly. In this paper, we will first explain the detailed formulation and algorithm of Non-Uniform Mesh. Next, examination of the reflection error from fine-coarse boundary because of the discontinuity is carried out. Then some test geometry are solved by using both uniform mesh and non-uniform mesh FDTD scheme to validate the results and check the accuracy of solution. We also examine the calculation accuracy due to mesh size ratio, and then investigation of how to determine the fine mesh region surrounding the object for a most small computation error will be carried out in this paper. In addition, the algorithm is demonstrated for several different antenna geometry.

We consider the problem of placing resources in a distributed computing system so that certain performance requirements may be met while minimizing the number of resource copies needed. Resources include special I/O processors, expensive peripheral devices, or such software modules as compilers, library routines, and data files. Due to the delay in accessing each of these resources, system performance degrades as the distance between each processor and its nearest resource copy increases. Thus, every processor must be within a given distance k1 of at least one resource copy, which is called the k-bounded placement problem. The structure of a distributed computing system is represented by a graph. The k-bounded placement problem is first transformed into the problem of finding smallest k-dominating sets in a graph. Searching for smallest k-dominating sets is formulated as a state-space search problem. We derive heuristic information to speed up the search, which is then used to solve the problem with the well-known A* algorithm. An illustrative example and some experimental results are presented to demonstrate the effectiveness of the heuristic search.

When the inter-slice resolution of tomographic image slices is large, it is necessary to estimate the locations and intensities of pixels, which would appear in the non-existed intermediate slices. This paper presents a new method for generating the missing medical slices from two given slices. It uses the contours of organs as the control parameters to the intensity information in the physical gaps of sequential medical slices. The Snake model is used for generating the control points required for the elastic body spline (EBS) morphing algorithm. Contour information derived from this segmentation pre-process is then further processed and used as control parameters to warp the corresponding regions in both input slices into compatible shapes. In this way, the intensity information of the interpolated intermediate slices can be derived more faithfully. In comparison with the existing intensity interpolation methods, including linear interpolation, which only considers corresponding points in a small physical neighborhood, this method warps the data images into similar shapes according to contour information to provide a more meaningful correspondence relationship.

Vanadyl-phthalocyanine (VOPc) single crystals were prepared on KBr substrate by molecular beam epitaxy (MBE). Their maximum size is 1380.16 µm3. The morphology of the VOPc single crystal was investigated from the results of UV/VIS spectra and RHEED. They suggest that the VOPc single crystal may be grown with pseudomorphic layers. The growing process was expained by Volmer-Weber model. The third order nonlinear optical property of VOPc single crystal was measured with Maker fringe method. The value of the third order optical susceptibility (χ(3)) of VOPc single crystal was estimated to be about 10-9 esu from the result of Maker fringe.

Layer-by-layer sequential adsorption process of polyelectrolytes had conventionally been used for the fabrication of the ultra-thin organic film formed by various polymers with different polarity of charge. In this study, hydrophobic Ruthenium complex monomer (tris (bilyridyl) ruthenium (II) hexafluorophosphate) was micelle-wrapped with an anionic surfactant, sodium dodecylbenzenesulfonate, and was assembled with PAH (poly (allylamine hydrochloride)) which has the opposite charge on ITO substrates. With this method, we succeed in fabricating ultra-thin organic films even when the adsorption material is not polymer but monomer. Moreover it was found that the bilayer thickness of the self-assembled (Ru micelle/PAH) was systematically changed by adjusting the solution pH of each bath. By using this process, EL device was fabricated by depositing the thin film of micelle-wrapping ruthenium complex monomer on ITO and formed Bi electrode on top of the film. Light emission was observed by applying voltage to this device.

Presented in this paper is a neural back propagation algorithm for reconstructing two-dimensional CT images from a small number of projection data. The paper extends the work in [1], in which a backpropagation algorithm is applied to the CT image reconstruction problem. The delta rule of the ordinary backpropagation algorithm is modified using a 'secondary' teaching signal and the 'Resilient backpropagation' scheme. Results obtained are presented along with those of two well known conventional methods: MART and EMML method. A quantitative evaluation reveals the effectiveness of the proposed algorithm.

A theoretical study on high slope-efficiency phase-shifted DFB laser diodes is presented. We have proposed a new grating structure called asymmetrically-pitch-modulated (APM) grating, and calculated its slope- efficiency and single-mode-yield. In order to take into account the modulated grating period; we have developed an F-matrix which directly includes a chirped grating structure. APM phase-shifted DFB laser diodes consist of a uniform grating in one half section of the cavity and a chirped grating in the other half. This structure causes asymmetrical field distribution inside the cavity and the optical output power from one facet is larger than that from the other facet. According to the simulation results, when the normalized coupling coefficient κ L is 3.0, the front-to-rear output power ratio is 2.6, while the single-mode-yield remains at 100%, and simultaneously the slope-efficiency improvement becomes 65% better than that of ordinary quarter-wave phase-shifted DFB lasers of the same κ L value.

We studied theoretically and experimentally an InGaAs/InAlAs/InP polarization-insensitive multiple quantum well (MQW) electroabsorption (EA) modulator operating over a very wide wavelength range in 1.55 µm wavelength region. One of the simplest possible potential-tailored quantum well, "pre-biased" quantum well (PBQW) is used to achieve wide-wavelength polarization insensitivity. PBQW is basically a rectangular quantum well with a thin barrier inserted near one edge of well. This thin barrier effectively introduces "pre-bias" to a rectangular quantum well and the same amount of Stark shift is achieved for electron-heavy hole and electron-light hole transition energies. By incorporating tensile strain into PBQW, polarization-insensitive modulation is achieved over 60 nm wavelength range, from 1510 nm to 1570 nm. This MQW-EA modulator plays an important role in wavelength division multiplexing (WDM) transmission and switching systems.

Principle of a single shot demultiplextion by means of time-to-space conversion was investigated using femtosecond nonlinear optical response of absorption bleaching of squarylium dye (SQ) J-aggregates. Spincoated films of squarylium dye J-aggregates on glass substrates exhibit efficient and ultrafast transmittance change, which recovers 73% of its initial level (0 fs) within 1 ps. A simple method for time-to-space conversion was applied for this film. We took our attention to one of the characteristics of femtosecond pulse, which is the spatial thinness in its propagation direction. Femtosecond pulses of a single pump pulse and train of four probe pulses were illuminated to the same area (diameter of 10 mm) of the surface of the SQ J-aggregates film. Direction of the probe beam was normal to the surface of the film and that of the pump beam was oblique angle in horizontal plane. Caused by spatial delay of a pump pulse due to the illumination in oblique angle to the film, four probe pulses with interval time of 1 ps (1 THz) meet separate places on the film. Because of the fast response of the SQ J-aggregates, the film picked out part of each probe pulse, which has narrower shapes in horizontal direction compared to the initial circular one by transmittance change of the film. The spatially separated four lines were observed by a CCD camera for an image of the transmitted probe pulse train. These results suggest that the response time of SQ J-aggregate film, which determines the horizontal width of each line, to be enough for demultiplexing of 1 THz optical signals.

In this letter, we describe a four thin-film-transistor (TFT) pixel circuit based on hydrogenated amorphous silicon (a-Si:H) technology for the active-matrix organic light-emitting diode (AMOLED) display applications. The circuit uses current-writing mechanism and can automatically adjust the threshold-voltage shifts of both the organic light-emitting diodes (OLEDs) and the TFTs induced by the circuit aging or process variations. Experimental results indicate virtually no variation of the output driving current after long-term bias-temperature-stress (BTS).

Efficient content-based retrieval of complex images is a challenging task since the detected object may appear in various scale, rotation and orientation with a wide variety of background colors and forms. In this paper, we propose a novel representation of objects with multiple colors, the spatial neighborhood-adjacency graph(SNAG), which can serve as a basis for detecting object by color contents from the candidate image. The SNAG consists of a set of main-vertices and two sets of edges. Each main-vertex represents a single color region of multi-colored object, and edges are divided into two classes: Neighborhood edges representing neighborhood relationship between two main-vertices with similar color, and adjacency edges representing adjacency relationship between a main-vertex and another vertex with different color. By investigating whether SNAG of object image is an isomorphic subgraph of SNAG of a candidate image, we can determine whether the similar object exists in the candidate image. In addition, we have also applied the proposed approach to a range of different object detection problems involving complex background, and effectiveness has been proved.

This paper proposes a Space-Time Object Model, an object oriented model that possesses space and time management mechanisms. The goal of this object model is to provide a common software infrastructure for implementing large-scale moving object simulations efficiently, such as car traffic simulations and disaster evacuation simulations, using a direct mapping scheme on a parallel and distributed computing environment. In this object model, the software infrastructure provides two principal functions, "Space Management" and "Time Management," which allows programmers to focus on application programming instead of parallel programming. Although there are several known infrastructure software, which provide the environment needed to develop and execute parallel and distributed simulations, they only provide a "Time Management" mechanism. In this paper, we present a Space-Time Object Model and an overview of a program called OSim, which is an implementation of the Space-Time Object Model. Then, we demonstrate the applicability and efficiency of this model by introducing the overview and evaluation results of a parallel car traffic simulation system using OSim.

This paper proposes an intelligent image interpolation method based on Cubic Hermite procedure for improving digital images. Image interpolation has been used to create high-resolution effects in digitized image data, providing sharpness in high frequency image data and smoothness in low frequency image data. Most interpolation techniques proposed in the past are centered on determining pixel values using the relationship between neighboring points. As one of the more prevalent interpolation techniques, Cubic Hermite procedure attains the interpolation with a 3rd order polynomial fit using derivatives of points and adaptive smoothness parameters. Cubic Hermite features many forms of a curved shape, which effectively reduce the problems inherent in interpolations. This paper focuses on a method that intelligently determines the derivatives and adaptive smoothness parameters to effectively contain the interpolation error, achieving significantly improved images. Derivatives are determined by taking a weighted sum of the neighboring points whose weighting function decreases as the intensity difference of neighboring points increases. Smoothness parameter is obtained by training an exemplar image to fit into the Cubic Hermite function such that the interpolation error is minimized at each interpolating point. The simulations indicate that the proposed method achieves improved image results over that of conventional methods in terms of error and image quality performance.

It is an important problem in signal processing, system realization and system identification to find linear discrete-time systems which are consistent with given covariance parameters. This problem is formulated as a problem of finding discrete-time positive real functions which interpolate given covariance parameters. Among various solutions to the problem, a recent remarkable one is a parameterization of all the discrete-time strictly positive real functions that interpolate the covariance parameters and have a limited McMillan degree. In this paper, we use more general input-output characteristics than covariance parameters and consider finding discrete-time positive real functions which interpolate such characteristics. The input-output characteristics are given by the coefficients of the Taylor series at some complex points in the open unit disk. Based on our previous work, we present an algorithm to generate all the discrete-time positive real functions that interpolate the input-output characteristics and have a limited McMillan degree. The algorithm is more general and simpler than the previous one, and is an important practical supplement to the previous work. Moreover, the interpolation of the general input-output characteristics can be effectively applied to the frequency-weighted model reduction. Hence, the algorithm makes a contribution to the problem from the practical viewpoint as well as the theoretical viewpoint.

This paper analyzes what structural features of graph problems allow efficient parallel algorithms. We survey some parallel algorithms for typical problems on three kinds of graphs, outerplanar graphs, trapezoid graphs and in-tournament graphs. Our results on the shortest path problem, the longest path problem and the maximum flow problem on outerplanar graphs, the minimum-weight connected dominating set problem and the coloring problem on trapezoid graphs and Hamiltonian path and Hamiltonian cycle problem on in-tournament graphs are adopted as working examples.