Masayasu Hata

AN ANOMALY OF ELF BAND VERTICAL MAGNETIC FLUX AS A PRECURSOR OF DOME FORMATION AT UNZEN VOLCANO AND ITS MODEL ANALYSIS

Abstract A peculiar environmental vertical magnetic flux anomaly was observed at the frequency of 223 Hz, which was 40 and 75 days before the 10th and 11th dome formations on Unzen volcano. The small but clear anomaly of order of 0.5 pT / Hz had appeared just on the vertical magnetic flux and never on the horizontal ones, and showed in many cases an intermittent oscillations of about a half- to 1-min period with almost the same size amplitudes. In this paper, we show a possibility that the vertical anomaly corresponds to the electromagnetic phenomena when magma passes the upper layer of aquifer under a volcano and give a simplified model which represents the phenomena and mechanism of generating the anomalous vertical magnetic flux. The anomaly lasted from the end of 1992 to September 10, 1994. After the termination of the appearance, the Unzen volcano weakened the activity and no events have been reported since then.

Extraction and computational estimation of malignant microcalcification on mammography

Mammography is one of the tools in the diagnosis of breast cancer. By a new method of mammography based on the soft X-ray and the ultrafine X-ray film, the X-ray exposure is reduced and the fine internal structure of the breast can be observed. With the increase of the subjects for breast cancer, it is required to improve the accuracy and efficiency of the diagnosis. A diagnosis-supporting equipment is required which provides an image display to assist in recognition of pathological changes, and provides an objective feature evaluation. This paper considers the microcalcification which is important in the diagnosis of the early breast cancer. The microcalcification appears as opaque points on the mammograph, and when the points are concentrated locally, it is diagnosed as malignant. n n n nAfter the emphasis by Laplacian processing, cell division was applied. The cell with aggregated microcalcification was extracted, and the image display was made so that the feature difference between cancerous and noncancerous lesions can be recognized. To arrive at a numerical representation of the feature difference, the following parameters were considered: (1) effective distance between cells; and (2) rate of change of the number of cells with regard to the change of the threshold. n n n nAs the result of processing 37 cases, including 14 benign cases and three normal cases, up to 14 of 15 malignant cases were able to be separated from other benign and normal cases, using those two parameters.

Property of the Legendre subsequence

The authors have proposed the use of subsequences of the Legendre sequences for spread spectrum communication systems, and discussed its randomness, correlation properties, frequency-domain peculiarities, and a new method of decipherment. This paper discusses the number of the prospective point and assumed solution, and gives a safety range of ratio (subsequence length l)/(prime number p).<<ETX>>

Quantitative expression of microcalcification distribution in mammograph by using fractal dimension

The authors discuss microcalcification observed in a mammograph which is important in diagnosis of early breast cancer. After emphasizing the digitized mammograph images by Laplacian operation, a threshold processing was applied to extract the microcalcifications. Although microcalcification opacity exists for both malignant and benign cases, there were differences in the distribution and the numbers of opaque points. To give a quantitative expression for the microcalcification, the data were evaluated by using fractal dimension. As a result of processing 25 cases, including 10 benign cases, up to 14 out of 15 malignant cases were able to be separated using the fractal dimension.<<ETX>>

Pre- and after-sign detection of earthquake through ELF radiation

A highly sensitive geomagnetic field detection system of order 0.01 pT at the ELF frequency of 225 Hz has been developed and set up in Ito city, Shizuoka prefecture, over four years and at Mt. Fugen, Nagasaki prefecture, over two years. From the ground ELF radiation, the authors detected precursors and after-signs of the advent of the tenth and eleventh lava domes and further even precursors of the fall of the eleventh lava dome at Mt. Fugen. Taking these observations into account, the authors propose a model of radiation due to volcanic activity. At Ito-city, they also detected precursor and after-signs of geomagnetic variations for five earthquakes out of six which occurred during August 30 to October 17, 1992, whose magnitudes were M=4.7, 6.6, 4.7, 4.6, 3.9, 5.1, excepting the case of M=3.9. The radiation showed a positive and negative correlation with the seismometer for the sequence of the earthquakes; the authors consider the reason for this and model the electromagnetic radiation.<<ETX>>

On the Realization of Received Quantum State Control by Unitary Transformation

Necessary and sufficient conditions of an optimum pair of signals for given decision operators are given. These conditions show what kind of signals are desired for the output of the unitary transformation in a received quantum state control system by unitary process in order to achieve the Helstrom’s bound. We show pictures of optimum signals which the conditions imply. Then we consider as examples two of received quantum state control systems by unitary process.

Line spectrum elimination of undesired signal by IIR adaptive digital filter

The authors propose a new method of line-spectrum elimination by making use of IIR adaptive digital filter (ADF) which is constructed of parallel connected second order IIR filters. And a new algorithm to control the poles of the IIR ADF is also proposed. The new algorithm utilizes the converged values of filter coefficients representing zeros of the IIR ADF as the frequency errors of the pole. The effectiveness of the new algorithm is shown in simulation results. Since the proposed algorithm can independently control each second order filter connected in parallel, the proposed IIR ADF can eliminate multiple narrow band signals.<<ETX>>

Improvement of the stability of the normalized LMS method under noisy environment

On the learning identification algorithm the value of echo return loss enhancement (ERLE) after saturation fluctuates for colored input signal under noisy environment. This paper proposes to improve the stability of ERLE by controlling the relaxation factor alpha , using the norm //x(j)///sup 2/ of input signal x(j).<<ETX>>

High-dimensional symmetric interleaved parity check code-general high-dimensional ring code

A new n-dimensional symmetric parity check code, named the ring code, is proposed. The code is constituted by means of the product space of cyclic-shifted versions of one-dimensional parity check codes, which shows crystalline structural symmetries. The ring code which is based on a two-dimensional ring code has a symmetrical structure. An n-dimensional ring code can easily be formed with (n-l)-dimensional ring codes. The reason why the authors propose this code is the high capacity of correcting burst errors, random errors and multi-burst errors for high-dimensional case. They propose the formation of a general n-dimensional symmetric ring code and show the features and performance of the high-dimensional ring code.<<ETX>>

A new adaptive algorithm based on conditioned normalized LMS method

A new algorithm for updating the coefficients of an adaptive FIR digital filter is modified by using the preset value p (constant). This value is determined beforehand from knowledge of the probability density function and variance of the input signal. In the new conditioned NLMS algorithm, the measured input signals square norm is compared with the preset value p. If the square norm is larger than p the coefficients of the filter are renewed. No renewal of the ADFs coefficients is done when the square norm is smaller than p. The simulation results and theoretical analyses show a good agreement. The saturated residual error in noisy circumstances is smaller than that of the unconditioned ordinary filter.<<ETX>>