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.

SiO2-added Ba ferrite (BaM:SiO2) films were prepared using BaFe12Si0.18Ox targets. BaM:SiO2 films exhibited perpendicular coercivity Hc⊥ of over 4.2 kOe and squareness ratio of 0.83, although saturation magnetization Ms decreased by about 15%. The angular dependence of coercivity Hc and remanent coercivity Hr were investigated to explain the magnetization reversal mechanism. Intergranular interactions in the films were also evaluated. The magnetization reversal mode of Ba ferrite films with and without SiO2 additives is not coherent rotation but appears to be the curling mode. The origin of the high coercivity of BaM:SiO2 films is different from that of Al-substituted Ba ferrite films. It seemed that SiO2 additives and the defects caused by them decreased Ms and prevented the expansion of reversed domains in the magnetization reversal process, similarly to some pinning effects, and caused high Hc⊥ of 4.2-5.1 kOe in BaM:SiO2 films.

An airborne X- and L-band synthetic aperture radar system was developed by the Communications Research Laboratory and the National Space Development Agency of Japan in their joint project from 1993 to 1996. It is installed in the airplane, Gulfstream II. In both the azimuth and range directions, the resolution is 1.5 m for the X-band and 3 m for the L-band. Both SARs can make fully polarimetric observations. The X-band SAR has a cross-track interferometric function. In this paper we describe the SAR system, its ground processing system, and its performance. We also discuss motion compensation and interferogram quality.

A novel algorithm associated with fractal preprocessors, wavelet feature extractors and unsupervised neural classifiers is proposed for detecting radar targets embedded in sea ice and sea clutter. Utilizing the advantages of fractals, wavelets and neural networks, the algorithm is suitable for real-time and automatic applications. Fractal preprocessor can increase 10 dB signal-to-clutter ratios (S/C) for radar images by using fractal error. Fractal error will make easy to detect radar targets embedded in high clutter environments. Wavelet feature extractors with a high speed computing architecture, can extract enough information for classifying radar targets and clutter, and improve signal-to-clutter ratios. Wavelet feature extractors can also provide flexible combinations for feature vectors at different clutter environments. The unsupervised neural classifier has a parallel operation architecture easily applied to hardware, and a low computational load algorithm without manual interventions during learning stage. We modified the unsupervised competitive learning algorithm to be applicable for detecting small radar targets by introducing an asymmetry neighborhood factor. The asymmetry neighborhood factor can provide a protective learning to prevent interference from clutter and improve the learning effects of radar targets. The small radar targets in Millimeter wave (MMW) and X-band radar images have been successfully discriminated by our proposed algorithm. The effective, efficient, high noise immunity characteristics for our proposed algorithm have been demonstrated to be suitable for automatic and real time applications.

In this paper, the improvement technique for a nonlinear parallel interference cancellation (PIC) receiver for a DS-CDMA system is studied, which cancels only the estimated multiple access interference (MAI) from specific users at each receiver stage. This technique was introduced as a PIC receiver using null zone hard decision in the proceeding of IEEE MILCOM '94, but the numerical results has not been fully provided with varying decision threshold. In this paper, the performance of the PIC receiver using null zone hard decision is shown in a Rayleigh fading channel. Also, a new PIC receiver with an adaptive decision threshold is proposed. In the proposed new PIC receiver, the decision threshold for partial cancellation is adjusted according to the statistic of its matched filter (MF) outputs. The BER of the proposed PIC receiver is obtained by simulation and compared with those of the conventional PIC receiver and the PIC receiver using null zone hard decision in a Rayleigh fading channel. It is shown that the proposed PIC receiver achieves better performance than the conventional PIC receiver and the PIC receiver using null zone hard decision in a Rayleigh fading channel.

This paper describes a DLL (Delay Locked Loop) circuit with the mixed-mode phase tuning method. The circuit accomplishes unlimited phase shift and accurate phase alignment through the coarse and fine phase tuning technique. It is based on a dual delay locked loop structure. The main loop is for generating coarsely spaced clocks and the second loop is for fast and accurate phase tuning with digital and analog phase detection. Simulations show that this circuit has 360 degree phase shift capability and can resolve 10 ps phase error using 0.6 µm CMOS technology.

Future high density magnetic recording requires a nanometer spaced head-slider interface, high track seeking velocity and high spindle speed. Such a combination greatly increases the likelihood of slider-disk and slider-particle-disk impact. Furthermore, the impact can generate high flash temperature and leads to data reliability problems, such as partial or full data erasure. This work report a method to conduct controlled experimental investigations into the possibility of such a data erasure even when the temperature is far below the Curie temperature. Results indicate that the high density magnetic transitions are of high likelihood of being affected by the flash temperature. Investigations also extended to micromagnetic modeling of the flash temperature effect. Results suggest that thermally induced local stress can play important roll in the data erasure process. Modeling results also exhibit that smaller grain size and higher recording density are also of higher likelihood of getting the transitions being affected by the flash temperature.

We have built a pulse-compressed high-resolution radar for surveying polar ice caps and ice sheet. In experiments with this instrument at the Agassiz ice cap, radio echoes from the bedrock and internal layers measured with high resolution. The resolution of the radar in ice is about 1 meter. The greatest depth from which signals from bedrock were received was more than 400 meters and that from which signals from internal ice were received was about 200 meters. Such performances are suitable for generating data that can be used for detailed comparison between ice core analysis and radar data. This radar is expected to be an effective tool for revealing the three-dimensional extension of event-layer in the ice core and to give information about the scattering mechanism of internal echoes.

This paper presents an efficient graph-based evolutionary optimization technique called Evolutionary Graph Generation (EGG), and its application to the design of fast constant-coefficient multipliers using parallel counter-tree architecture. An important feature of EGG is its capability to handle the general graph structures directly in evolution process instead of encoding the graph structures into indirect representations, such as bit strings and trees. This paper also addresses the major problem of EGG regarding the significant computation time required for verifying the function of generated circuits. To solve this problem, a new functional verification technique for arithmetic circuits is proposed. It is demonstrated that the EGG system can create efficient multiplier structures which are comparable or superior to the known conventional designs.

In this letter, a new rapid converging method based on orthogonalization is proposed. Our approach is to find the near-optimum coefficient values during training period, and then use them as the initial values of the LMS algorithm. The numerical results show that the rapid convergence speed of the proposed scheme does not depend on the eigenvalue spread.

Recently, cerebral disease is being a serious problem in an aging society. But, rank evaluation of cerebral disease is not developed and therefore rehabilitation is hard. In this study, we try to assess slight cerebral disease by taking notice of recognition mechanism of face and realizing face image synthesis using computer technology. If we can find a slight cerebral disease and rank evaluation, we can apply to rehabilitation, and a load of medical doctor and patient decreases. We have obtained a result by the experiment, so we report it.

We report a directly deposited dielectric multilayer onto an end face of a fluorinated polyimide optical waveguide by ion beam sputtering process. This dielectric multilayer (Ta2O5/SiO2) acts on a wavelength separation filter which passes 1310 nm wavelength signal and reflects 1550 nm wavelength signal.

In this paper, some properties of domain tree languages of top-down pushdown tree transducers (domain(t-PDTT) or t-PDTTD) are shown. It is shown that (1) for any L1, L2 in context-free language (CFL), L1L2yielde(t-PDTTD) (where yielde is an extended yield), (2) yielde(t-PDTTε0DF) is closed under homomorphisms, where t-PDTTε0 is a t-PDTT which can not proceed generations after reading a constant symbol σ and t-PDTTε0DF denotes a domain tree language of t-PDTTε0 with a final state translation, and (3) yielde(t-PDTTε0DF) is the class of recursively enumerable languages, and consequently yielde(t-PDTTD) is the class of recursively enumerable languages.

In this paper, we describe a method of determining meat quality using the concepts of "marbling score" and texture analysis. The marbling score is a measure of the density distribution of fat in the rib-eye region. Based on the results of an investigation carried out by handing out questionnaires to graders, we consider the marbling of meat to be a texture pattern and propose a method for the implementation of a grading system using a texture feature. In this system, we use a gray level co-occurrence matrix as the texture feature, which is a typical second-order statistic of gray levels of a texture image, and determine standard texture-feature vectors for each grade based on it. The grade of an unevaluated image is determined by comparing the texture-feature vector of this unevaluated image with the standard texture-feature vectors. Experimental results show the proposed method to be effective.

A Rayleigh lidar (laser radar) system was developed and is now working well for temperature observations of the middle atmosphere at Poker Flat Research Range near Fairbanks, Alaska (65.1 N, 147.5 W). A comparison of lidar data and balloon sonde data showed good agreement in overlapped altitudes. The atmospheric fluctuations are detected in the temperature profiles obtained by the Rayleigh lidar and these are useful for the study of gravity waves. A Rayleigh Doppler lidar for wind measurements of the middle atmosphere is under the phase of development. The expected accuracy in measurements of horizontal winds up to an altitude of 60 km is smaller than 6 m/s in 2 hours observation. The system will be operated at Poker Flat after the completion of development. The combination of these lidars and radars installed at Poker Flat, give us chances of simultaneous observations of the structure and dynamics of the atmosphere in broad range of altitudes. Here, we give descriptions of the Rayleigh lidar and the Rayleigh Doppler lidar for the observations of the Arctic middle atmosphere at Poker Flat.

This paper investigates an obstructed radio channel by foliage for LMDS (local multipoint distribution services) where a relative evaluation of attenuation characteristics of foliage at 29.5 and 5 GHz is performed. Results show that the attenuation in dB should be treated statistically as Rician distribution. It is also found that swaying foliage in wind causes a significant channel fading at 29.5 GHz, ranging over 10 dB, while the fading depth at 5 GHz is approximately 2 dB.

A low bit-rate encoding method which yields a good performance in edge reconstruction while achieving a high compression is proposed through MTF function and the spatial anisotropy of human vision. Human visual weighting factors applied to sub-blocks within each subband in wavelet domain are produced by the spatial anisotropic-filter, then a good perceptual performance can be obtained.

We analyze the performance of soft handoff used as intergroup handoff in the fiber-optic cellular system. Performance is evaluated in view of blocking and handoff refused probability. The numerical results show that the smaller the handoff region or the more the channel, the larger the system capacity.

This paper concentrates on the model useful for analyzing the error performance of M-estimators of a single unknown signal parameter: that is the error intensity model. We develop the point process representation for the estimation error, the conditional distribution of the estimator, and the distribution of error candidate point process. Then the error intensity function is defined as the probability density of the estimate and the general form of the error intensity function is derived. We compute the explicit form of the intensity functions based on the local maxima model of the error generating point process. While the methods described in this paper are applicable to any estimation problem with continuous parameters, our main application will be time delay estimation. Specifically, we will consider the case where coherent impulsive interference is involved in addition to the Gaussian noise. Based on numerical simulation results, we compare each of the error intensity model in terms of the accuracy of both error probability and mean squared error (MSE) predictions, and the issue of extendibility to multiple parameter estimation is also discussed.

In Optimistic Two-Phase Locking (O2PL), when a transaction requests a commit, the transaction can not be committed until all requested locks are obtained. By this reason, O2PL leads to unnecessary waits and operations even though it adopts an optimistic approach. This paper suggests an efficient optimistic cache consistency protocol that provides serializability of committed transactions. Our cache consistency scheme, called PCP (Preemptive Cache Protocol), decides whether to commit or abort without waiting when transactions request commits. In PCP, some transactions that read stale data items can not be aborted, because it adopts a re-ordering scheme to enhance the performance. In addition, for re-ordering, PCP stores only one version of each data item. This paper presents a simulation-based analysis on the performance of PCP with other protocols such as O2PL, Optimistic Concurrency Control and Caching Two-Phase Locking. The simulation experiments show that PCP performs as well as or better than other schemes with low overhead.