In his recent work, Monopoli seems to have established the design method for model reference adaptive control for single-input single-output linear systems. The basis of his method is validated mainly in the design of a special system of which the difference between the degrees of the denominator and the numerator polynomials of the plant transfer function, so called the “relative degree”, is one. It has been seen that the design method becomes extremely complicated with an increase of the relative degree. A design method for model reference adaptive control systems using an adaptive observer to avoid this difficulty is discussed in this paper.

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In this paper we consider the behavior of the output of a multivariable feedback system at the beginning of the response when inputs are a polynomial function of time.
It is shown that this initial behavior can be computed very easily from the open-loop transfer function matrix of the system. Using this result, so called “a reverse response” to a step function input in scalar systems is extended to the case of multivariable systems, and conditions that a feedback system has no reverse response to any vector step function are obtained.

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This paper considers the parametric structure of the controllability of linear time-invariant systems. The set of (A, B), controllable linear time-invariant multi-input systems, is divided into several equivalence classes through controllability indices, These equivalence classes are distributed in the parameter space. The elementary algebraic geometry resolves the algebraic relations of the parameters (A, B) with respect to its controllability indices, and its structure in the parameter space.
The set of (A, B) with the same controllability indices is the intersection of the several algebraic open or closed sets depending on its indices. The insensitivity relation between the controllability indices by the, parametric perturbation is defined based on the algebraic set property in the elementary algebraic geometry.

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The necessary and sufficient condition for decoupling of multivariable linear time-varying systems with time delays in the control variables is presented for the limited case in which the control system has no state feedback scheme. Some algebraic properties associated with the time delay operator are rigorously investigated to ensure the mathematical procedure leading to the theorems for decoupling condition. A numerical example is shown to demonstrate the fact that the theorems formulated in this paper can cover more extensive decoupling problems than the theory given by Iwai et al. which presents a sufficient condition for decoupling of multivariable linear time-varying systems with state feedback.

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A model reference technique is used to develop adaptive identification schemes for multivariable continuous linear dynamical systems which contain unknown parameters linearly.
In this paper, the conditions which assure the identifiability of unknown process parameters are obtained and four types of identification schemes are proposed. It is proved by the Liapunov's direct method that the estimation errors of these types are asymptotically stable in the large when the measurement noise is free.
This tequnique is also extended so that it can apply to a sampled data system and consequently, the technique becomes available in real time estimation using a digital computer.
As an application of this adaptive identification approach, the physical parameters of a parallel heat exchanger are identified using a fourth order approximate model obtained by the Method of Weighted Residuals. The results show that this approach is sufficiently useful to the parameter identification of a distributed parameter system.

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A new technique is proposed for designing the two-dimensional digital filters which will be applied to play a central role in image processing. Basic ideas of this technique are the separable sum of one-dimensional recursive filters and the zero phase sum. So, in this technique, the difficulty of stability problem of two-dimensional recursive filters does not arise and the implementation of the filters becomes simple. And because of the structure of the zero phase sum, the filtered images by this filter are not degraded by a phase error.
Filters having an arbitrarily prescribed frequency response are designed to minimize the error criterion function by using the non-linear optimization algorithm.
The frequency responses of resulting filters and the results of the application of these filters to some images are illustrated. Experimental results show that the filters designed by this technique give good responses approximating the desired non-separable frequency responses and are sufficiently practical to be applied in image processing.

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A new method for image data compression and reconstruction is described. In this method two-dimensional interpolative linear estimation is employed to obtain a large data compression ratio. The gray level of each pixel is estimated by taking a linear weighted summation of gray levels of its neighbours on all sides. The weight coefficients are determined so that the mean square estimation error is minimized.
The optimal estimation errors are evaluated pixel by pixel, and the obtained error image is added to the original image multiplied by a small positive weight. Then, this compressed data are transmitted together with the estimator weight coefficients.
To reconstruct the original image from the compressed data, an iterative algorithm based on the conjugate gradient method is used. It is shown that the addition of original image information to the estimation error data reduces drastically the iteration number required in the reconstruction process at a small increase of the data amount to be transmitted.

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It is known that the detection of a random signal s(t) in the presence of an additive background noise n(t) is performed on the basis of the cross-correlation a₁ of an input signal x(t)=s(t)+n(t) and the output signal of a linear filter driven by x(t).
This paper presents a new method to determine an impulse response g(t) of the linear filter in such a signal detection system; that is, g(t) is matched to the auto-correlation function of s(t) under the condition that g(t) is orthogonal to the auto-correlation function of n(t). Therefore, a₁ depends only on the power of s(t), but does not depend on n(t) even if the level of n(t) varies. As a result, by this method it is possible not only to detect the presence or absence of the random signal hurried in the background noise, but also to measure the power of the signal.
As an application of this method, the detection of knock in a gasoline engine is attempted. The level of an engine vibration under knock free conditions, which is regard as the background noise from the knock-detecting point of view, always varies according to the engine speed. The experiment shows that this method is applicable to detect the knock and to quantify the intensity of the knock under these variable running conditions of the engine.

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This paper deals with a newly developed methodology and a related system for the automatic pattern recognition of machine parts, etc., on the basis of the degree of similarity. In the methodology, two feature parameters are extracted. These two parameters are the pattern-classification value S and the group-classification value N. The pattern-classification value is obtained from the ratio of the area to the product of the largest width multiplied by the largest height of the projection of the pattern on the reference line. The group-classification value is obtained by the second differentiation of the projection. Since the patternclassification value generally varies with the postural angle of the shape, the average value S and the range of variance ΔS of the pattern-classification value are defined.
A pattern is mapped firstly on the feature extraction space (named E-space) decided by using three parameters S, ΔS and N. Secondly, the E-space is mapped on the sensing filter space (F-space). The similarity is calculated by the distance between the two patterns mapped on the F-space. In order to match the calculated similarity with the similarity recognized by human, the characteristics shown in the similarity recognition of various kinds of shapes have been examined by a few adults and the experimental results are taken into account in developing the system. By the developed pattern recognition system, one pattern can be recognized in less than 4 seconds to be classified according to the 22 kinds of matching patterns memorized in the minicomputer.

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As an approach to the analysis of complex systems such as social, economic and environmental systems, a lot of complex and ambiguous multidimensional data must be treated. Therefore, a technique of data presentation suited to the visual sense is required. But there has been almost no systematic study of expressing data, because even in systems engineering, not much attention has been paid to this area of study.
This paper describes the use of a face pattern, which is illustrated by a newly developed method, for expressing the various states of a complex system and their processing. This face pattern is based on the results of the analysis of facial expressions. Some technique of assigning data components to facial features, which make use of the characteristics of facial expressions, are proposed in this paper. As a practical application of the present Faces Method, the emission data of six air pollutants of Tokyo's 23 wards are expressed in the form of various facial expressions, which are classified by a developed classification procedure, and the resulting characteristics of the emission data are extracted from the facial expressions. These results are compared with the results obtained from cluster analysis and principal component analysis. Moreover, one dimensional scaling of the classified facial expressions is tried to evaluate the emission data. The efficiency of the Faces Method is investigated through these experiments.

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In this paper, as an application of a failure detection method to a man-machine system, an on-line experiment is described to show how a man's attention is distracted. The outline of this experiment is as follows: a subject performing a tracking action is given a side task. The distribution of the tracking errors is assumed to be normal whether the side task is given or not. And it is assumed that the mean value and/or the variance of the tracking error curve would change with an intervention of side task. These changes are detected by the modified Wald's SPRT. The results are only qualitative but show that the distracted attention will show directly on the tracking error curves in some cases. Therefore the method in this paper is simple and effective as compared with the method which identifies the human and detects shifting attention by the change of the parameter identified.

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This paper deals with the information transmission characteristics of a two-dimensional electrocutaneous communication method using magnitude and frequency simultaneously. Firstly, the channel capacity of a two-dimensional electrocutaneous communication system is discussed. Secondly, the maximum information transmission rate is estimated from a category detection test. Finally, the reaction time, the time between the presentation of a two-dimensional electrocutaneous stimulus and a detectable response to it is measured and the maximum information transmission rate per second is calculated.
The following results are obtained; (1) The channel capacity of the two-dimensional electrocutaneous communication system is the summation of the channel capacities of both the magnitude dimension in a minimum frequency level and the frequency dimension in a minimum magnitude level. Its value ranges from 5.6 to 6.0 [bit/symbol] for four subjects. (2) The maximum information transmission rate estimated from the category detection test is 2.7-3.2 [bit/symbol] for three subjects. It is larger than the individual one-dimensional information transmission rate, but not more than the sum of the both. Especially, when the frequency and the magnitude dimensional stimuli are presented simultaneously, the information rate transmitted only through the magnitude dimension has a tendency to decrease due to the interaction between the two dimensions. (3) The reaction time of the two-dimensional category detection test is 300-970[ms] for N_m=2∼4, N_f=2∼4, where N_m and N_f indicate the numbers of categories of magnitude and frequency, respectively. On the basis of the above results, the upper limit of the presented number of the two-dimensional categories is a paired N_m=3, N_f=3, which can be more advantageous for the simultaneous presentation of two-dimensional stimuli from the standpoint of increasing the information transmisson rate per second than for the sequential presentation of them. For N_m=2∼3, N_f=2∼3 information transmission rate per second is found to be 4.5 [bit/symbol] to 6.4 [bit/symbol].

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The density of LPG (liquid petroleum gases) was measured by vibrating density meter. This meter has a spool as the sensor that vibrates like a bell and its frequency depends upon the density of the sample fluid surrounding the spool.
The feature of this device is the mechanical strength because the fluid is filling up inside and outside of the spool and the performance is not influenced by a high pressure.
The vibrating density meter was calibrated by some liquid such as water, benzen, ethylalcohol, etc, whose density had been determined by using a pycnometer.
The density of liquid petroleume gases was measured by this meter. The experimental values obtained at 20°C were 578.3kg/m³ for n-butane (purity: 99.68%) and 500.3kg/m³ for propane (purity: 99.66%) respectively. They agree well with the values measured by hydrometers and hydrostatic method with the accuracy better than 0.2kg/m³.

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Recently, closed-loop type material testing stands and vibration testing stands are widely used, and electro-hydraulic servo systems are generally adopted in the large-scale equipment.
In these systems, it should be noted that the characteristics of their test objects have large influence on the input-output relation of the systems. This paper deals with the load-insensitive servosystem using a servovalve for material testing equipment. Firstly, it is pointed out that the relation between the input current and the output flow rate of the servovalve is dependent on the load pressure. Secondly, compensating methods are proposed to obtain the output flow rate proportional to the input current, and to remove the effect of the compressibility of the fluid in the cylinder. Thirdly, the hydraulic servosystem is constructed for experiment on the basis of these compensating methods. Finally, it is clarified experimentally that without adjusting the system parameters, this system can give the desired dynamic strain to the test objects regardless of the wide variation of their elasticity within the range of load force less than 3KN and frequency less than 40Hz.

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An analog divider which is suitable for online measurement of transient contact resistance between the metal pieces to be spot-welded is proposed. It is known that the transient value of the contact resistance in spot-welds is one of the most important clues to estimate the quality of spot-welded nugget.
However, the contact resistance changes so rapidly during spot-welding that it is very difficult for a user of the conventional equipment to carry out the on-line measurement of the transient contact resistance.
From this point of view, the authors have constructed an analog divider suitable for such measurement, and show some typical experimental results obtained.
Using this divider, a certain relation has been found between the pattern of transient change of contact resistance and the results of spot-welding. This suggests us a possibility of contriving some feedback control system in the spot-welding equipment.

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The second-order lag plus dead time model is commonly used in many chemical processes. In this paper, first, a simple approach to evaluating the second-order transfer function is proposed. This method contains the concept of moment. Next, the general solutions that give a set of optimal discrete PID control parameters for the second-order DDC system are reported. By applying the above methods to the actual furnace model plant data, we confirm the optimal setting.

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The requirement for a stable startup, a stable shutdown and for a wide range power changing is urgent in the recent thermal power plants. In this paper, a new control system fulfilling the requirement is discussed and proposed for steam turbine which is one of the most important parts in a thermal power plant.
First, dynamic characteristics of a turbine are analyzed and the problems which must be taken into consideration at synthesis of a control system are clarified. Especially, non-linear characteristics of the revolutional speed and the output power in the case of combinational manipulation of several control valves during turbine startup and shutdown as well as the wide range output power change are discussed and clarified. The results of the investigation of dynamics are reflected upon the development of a new control system (governor).
Finally, the digital turbine governor with the following features is proposed.
(1) A wide coverage of control functions including turbine startup, shutdown and a wide range output power changing.
(2) Coexistence of flexibility and standardization of control functions by the introduction of microcomputers.
(3) High reliability by a redundant system.
The expected performance was actually confirmed by the operation of the newly developed turbine governor at an actual thermal power plant.

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This paper deals with an analytical and experimental study on the hard self-excitation phenomenon in the hydraulic unity feedback servomechanism operated by a spool valve with asymmetrical underlap. The nonlinear equations describing the system performance are numerically solved by Runge-Kutta-Gill method. Conclusions obtained are as follows:
(1) The stability of the neutral position of the valve is improved by increasing the supply underlap. But delivering a large step input beyond the critical value Z_cr to the system stabilized as mentioned, will often start a self-oscillation to lead the system into instability. This phenomenon is the so-called “hard self-excitation”.
(2) As the supply underlap ε_s increases, the critical value Z_cr of the step input required to excite the hard self-excitation increases.
(3) For a small underlap ratio λ(=exhaust underlap ε_e/supply underlap ε_s), the hard self-excitation appears and for a large value of λ, the oscillation changes into the soft self-excitation.

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The pneumatic pilot valve is one of pressure control valves and is used in pneumatic control instruments. The valve amplifies nozzle back pressure. This report deals with the so-called nonbleed type pilot valve with nonmetallic diaphragms. It is an advantage of this valve that it controls the large output flow rate consuming little control air. The valve contains two diaphrams for receiving the input and output pressures. There are three modes of actions with the valve; namely, (1) the steady mode when the both supply and exhaust valves are closed (2) the charge mode when the input signal increases and the supply valve opens, and (3) the discharge mode when the input signal decreases and the exhaust valve opens. The paper studies the characteristics of the valve under these three acting modes. A valve action of this type is constituted with these different modes, so there exists a strong non-linearity. In the charge and discharge modes, the pressure near the valve slit decreases steeply because the air speed is very high. The resultant force acts to close the valve. This force is called Bernoulli's force in fluid mechanics. Because it is difficult to estimate the magnitude of the force theoretically, we obtained it by experiment. The output flow rate is influenced by this force directly and decreased by about 20%.
The action of the pilot valve was generally described as a first order system neglecting influences from loads. But the output pressure influences the valve displacement and the output pressure is determined by the pressure-flow characteristics of the load. Hence it should be necessary to regard the output pressure as a feed-back signal to the valve. From this point of view we proposed a new graphic model of the pilot valve.

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An electronic relay with hysteresis which consists of an integrated comparator (IC comparator) and a positive feedback path, and its application circuit, that is, a pulse ratio modulator are analized. These kinds of circuits have been used in various fields, since they have the simple construction and dissipate very little power, and since the reliability of IC has remarkably been improved.
The operative properties of such circuits, however, were not always obvious owing to the nonlinearities and the complexity of the operating equations. And it was difficult to solve even numerically these equations. In this paper, a large signal DC transferring element and a transfer lag element constitute the model of the IC comparator. The numerical analysis using the model shows the hysteresis characteristics of the electronic relay depending on the variation velocity of the input signal. In the application of GPSS to analize the pulse ratio modulator, the responses to some input signals including not only the simple but the compound oscillations and the transient processes are simulated in the practical CPU time and with a reasonable accuracy. Among other applications, the present methods may be convenient in the analysis and design of switching-type power circuitry.

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In this paper, we consider the concept of convex dependence on n-attribute space and derive convex decompositions for n-attribute utility functions. Then we show various properties of the convex dependence on n-attribute space. The concept of the convex dependence covers a wide range of trade-off analysis and generates various decompositions of an n-attribute utility function u (x₁, x₂, …, x_n), which include Keeney's additive, multiplicative or multilinear decomposition and Fishburn's bilateral decomposition as the special cases.

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