Mitsuo Ohta

A methodological trial of regression analysis with higher order correlation between electromagnetic and sound waves leaked by a VDT in an actual working environment

In this study, a stochastic methodology to grasp the mutual relationship between electromagnetic and sound waves leaked by a VDT in an actual working environment is discussed, especially through a new trial of regression analysis, reflecting not only the linear, but also the non-linear correlation information. More concretely, in order to evaluate the related inverse regression function and predict the specific probability distribution by employing the regression function or the conditional probability distribution, the method on how to utilize the linear and/or non-linear correlation information among them is also pointed out. The validity and effectiveness of our proposed method is confirmed through a principle experiment by applying it to the observation data leaked by a VDT with a television game in the room of an actual working environment.

Preparation of p-Type CdS Thin Film by Laser Ablation

A new method to prepare p-type CdS thin film was investigated, in which the laser ablation was applied to a mixed target of CdS and Cu. The p-type CdS film was obtained from a target containing more than 5 at% Cu. Composition analysis showed that Cu content in the film was about one-fifth of that in target. The formation of p-type CdS film was also confirmed by the photovoltaic effect of the p-n junction which was constructed by laminating n-type CdS film and p-type CdS film.

Statistical estimation of road traffic noise in an arbitrary sound propagation environment by use of Stratonovich's theory for a random points system

Abstract To date, many methods for estimating the statistics of road traffic noise have been proposed involving the introduction of particular vehicle distribution models, such as an equally spaced model, an exponentially distributed model, or an Erlang distribution type model, in a simplified sound propagation environment such as a free sound field. In certain more generalized studies based particularly on the latest Erlang distribution type model (i.e., a Gamma distribution model), only the first and second order moments of the sound intensity fluctuation, which can be derived from the statistical information on the location of only one and/or two vehicles (e.g., the distributions of the positions of the vehicles and of the distance between two arbitrary vehicles moving in the same direction) have been taken into consideration. The higher order statistical properties of traffic noise are important, however, if one wishes to take into account the form of the noise distribution, from which any noise evaluation index must be derived. Thus, this paper is devoted to considering the relationships between the multi-dimensional correlation properties of the sound intensity and the higher order information on the flow of vehicles by use of Stratonovichs stochastic theory for a random points system. The relationships between the theoretical results and those of well-known previous studies are discussed for several lower order moments.

A Digital Filter for Stochastic Systems with Unknown Structure and Its Application to Psychological Evaluation of Sound Environment

The actual sound environment system exhibits various types of linear and nonlinear characteristics, and it often contains an unknown structure. Furthermore, the observations in the sound environment are often in the level-quantized form. In this paper, a method for estimating the specific signal for a sound environment system with unknown structure and the quantized observation is proposed by introducing a system model of the conditional probability type. The effectiveness of the proposed theoretical method is confirmed by applying it to the actual problem of psychological evaluation for the sound environment.

A fundamental study on the statistical evaluation of receiver response for an electromagnetic wave environment in multi-dimensional signal space : Theory and basic experiment

In this paper, a statistical electromagnetic (abbr., EM) interference study is constructed mainly from a theoretical viewpoint on the basis of N-dimensional random walk problem in multi-dimensional signal space. First, a characteristic function of the Hankel transform type matched to this EM environmental study is introduced especially in an extended form of D. Middletons basic result. Then, the probability density function (abbr., pdf) is explicitly derived for the EM random fluctuation with a power scaled variable (or an effective value) measured by a receiver with a mean square operation. The proposed theory is verified by showing the agreement with one of D. Middletons great researches as a special case of the proposed expressions. Moreover, the effectiveness of the proposed method is experimentally confirmed through an acoustic type simulation of EM environment and the application to a simplified actual EM environment with joint space-time non-Poisson interference as one of the same wave motion typ...

Various regression characteristics with higher order among light, sound and electromagnetic waves leaked from a VDT — measurement and signal processing in the actual working environment

In this study, a regression analysis method considering not only a linear correlation but also the higher order nonlinear correlation information is proposed in a form suitable for signal processing by using a digital computer and digital level observation, especially in order to find minutely the mutual relationship among light, sound and electromagnetic waves leaked from electronic information equipment. More specifically, an extended type regression analysis method hierarchically reflecting various types of correlation information is theoretically derived by introducing an expression on the multi-dimensional probability distribution in an orthogonal expansion series form with discrete level type. The effectiveness of the proposed theory is experimentally confirmed by applying it to the observed data leaked from a VDT in the actual working environment.

A STATISTICAL THEORY FOR ROAD TRAFFIC NOISE BASED ON THE COMPOSITION OF COMPONENT RESPONSE WAVES AND ITS EXPERIMENTAL CONFIRMATION

Abstract None of the existing standards, which express the needs of engineers, consider correlation properties of traffic noise. But the correlation properties of traffic noise often seem to have a fundamental importance in certain engineering fields of noise control, such as the design of barriers for sound insulation and the detection of voices in noisy out-of-doors situations. In this paper, firstly, the correlation properties in the time domain and the frequency characteristics of the sound intensity at an observation point are discussed in the general case: i.e., for arbitrary values of quantities such as the propagation characteristics of the traffic sound energy, the numbers of lanes of road and of types of vehicles, the mixture ratios of vehicle types, the average number and respective acoustic power distributions of vehicles travelling with specific velocities on each lane of the road, the lengths of the straight sections of the road and the distance from the observation point. Next, the equivalence problem of replacing the several lanes of the road by a representative single lane is also discussed in detail, as an application of the statistical method. Finally, the values obtained from the theoretical expressions for several kinds of correlation functions of lower and higher orders are compared with experimental values, as obtained by use of the digital simulation technique.

Digital simulation of a white noise model formed of uniformly almost periodic functions

Starting from a criticism of the Rice representations of normal random noise, a new mathematical model of white noise expressed in terms of uniformly almost periodic functions is obtained. By means of digital simulation it is confirmed that the model exhibits white noise characteristics.

Multi-Dimensional Generalization in Space and Time Domains for Middleton's Study in Stochastic Evaluation of Correlative Many Em Noise Processes - Abstract

in this paper, a statistical study on correlative many electromagnetic (abbr., EM) interferences is given mainly from a theoretical viewpoint on the basis of random walk problem in multi-dimensional signal space, along to the same study line as in our previous paper. First, a joint multi-variate characteristic function of Hankel transform type matched to many kinds of EM environmental fluctuation waves is introduced especially in an extended form (in space and time domains) of D. Middletons basic result. Then, a joint multivariate probability density function (abbr., pdf) is explicitly derived for correlative many kinds of EM random fluctuations with a power scaled variable (or an effective value) observed by many receivers of mean square operation type, especially by laying emphasis upon a derivation of explicit pdf expression for correlative two kinds of EM fluctuation waves. The effectiveness of the proposed method is experimentally confirmed through an acoustic type simulation experiment with joint s...

Time series prediction method for stochastic acoustic signals by the use of an adaptive function model

Abstract In principle, some kinds of correlations can be found between the past data and the future value in the actually measured acoustic signals. This paper describes a new trial of predicting the fluctuation of a stochastic acoustic signal by extracting the information on many correlation properties from its measured past data. More explicitly, the prediction algorithm is proposed in a general form of series expansion type with a linear combination of newly introduced adaptive functions, with the use of a generalised error evaluation criterion. Finally, the validity and effectiveness of the proposed prediction method have been confirmed by a computer simulation and an application to the actual stochastic acoustic signal measured near a national main road in Hiroshima City.