Control performances of software servo systems depend on the resolution of the generated torque which is commanded via A/D and D/A converters. In this paper, the mathematical model of software servo system considering the torque quantization error is derived. The required torque resolution is clarified when the control performances, such as steady state error and fluctuation to the ramp position reference, are given. The analysis in this paper is useful in determining the required resolution of A/D and D/A converters.

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In this paper we propose a numerical computer method of the formal linearization for nonlinear systems by using the discrete Fourier expansion. A nonlinear system is described by a system of nonlinear ordinary differential equations. A linearizing function is given by a sequence of the trigonometric functions. The nonlinear terms of the differential equations are expanded into finite sums of the trigonometric functions by the method of the discrete Fourier expansion. As a result, a formal linear system is derived from the given nonlinear system.
A computer algorithm of the linearization is acquired and numerical computation is easily carried out with the aid of computers. Besides, as the application of the linearization, both a nonlinear observer and a nonlinear filter are also synthesized in the paper. Examples show that the accuracy of the method is improved as the order of the trigonometric functions increases.

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The satisfiability problem (SAT) is one of the important problems in the field of computer science, since it is well known NP-complete problem. The problem is well studied and many valuable results are reported in the literature. We have already proposed IEMSAT algorithm as one of SAT algorithms. Recently, J. N. Hooker made a study of resolution for a set of β clauses. A β clause is a clause that has an additional quantitative condition. The condition is that a β clause is true if and only if at least number of β literals in the clause are true. He also referred to β SAT problem that is SAT consists of β clauses. He, however, did not propose efficient algorithm for it as yet.
This paper intends to present β SAT algorithm ( IEMBSAT ) that is an extended variant of IEMSAT. Some relations between a β clause and a clause are also clarified. Some computational experiments are made to show the effectiveness of IEMBSAT.

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In this paper, we attempt to estimate the state of a finite state system which has some finite states and changes its state from one to another as time varying. The method to estimate is based on the some feature parameters extracted from observed time series signal. As the feature parameters aren't sufficient to distinguish one state from the others, we encounter the nonspecificity which represents difficulty in affirming in which state the system is. To take consideration of this kind of fuzziness, an algorithm, joining fuzzy clustering to fuzzy finite state transition model, is suggested. In this estimation method, time series behavior patterns are expressed as fuzzy clusters, each behavior to be processed is represented as possibilities belonging to the clusters, and the rules about the state transition is described as a fuzzy finite state transition model whose input is time series behavior. Calculating the possibilities of states of that model and evaluating the nonspesifisity, the finite estimation is done. It is reported that this algorithm is effective in a practical problem, detecting error of a counter which counts magnetic cards.

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This report describes a wide range air-fuel ratio sensing technology used yttria stabilized zirconia concentration cell with limited diffusion porous layer and its driving and signal processing module used micro-computer. This sensing system is effective when it is applied to air-fuel ratio control of engine which is required to optimize exhaust emission, fuel consumption rate and output power of engine.
The possibility of this air-fuel ratio sensing method can be realized wide rangeability by a potentialized ground of the cell and high accuracy by self air-calibration during deccelerating fuel-cut. That is to say, it is able to reduce initial variability of sensors in production line and long term output change of sensor on board.

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The ablation capability of various excimer laser radiations to burn eschar was experimentally investigated in vitro to develop rapid and precise removal of burn eschar (debridement). Full thickness burn and normal skin of rabbit were used as samples. We used ArF (193nm), KrF (254nm), and XeF (351nm) excimer lasers for the ablation. The fresh resectioned skin samples were employed in almost measurements. The ablation capability was investigated by laser drilling. The ableation crater was evaluated by its depth or etching rate and coagulation layer thikness at side and bottom of the crater. Typical ablation conditions were up to 5J/cm² in fluence and 50Hz in repetition frequency. Despite the ArF laser had precise ablation with no thermal damage, the ablation rate was restricted up to 2μm/pulse. The KrF laser ablation showed high ablation rate up to 13μm/pulse with thin coagulation layer and 50% affinity against normal skin. The XeF laser had poor capability both in the ablation rate and coagulation layer. These ablation characteristics may be explained by absorption characteristics of the burn eschar and normal skin for individual laser wavelengths. The results indicated that the KrF laser was the most applicable laser for burn eschar removal. Higher irradiation fluence with lower repetition frequency might improve the KrF laser ablation performances.

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In adaptive algorithms, there are some problems, such as the improvement of the convergence property and the reduction of the computational requirements per sample time, to be resolved. This paper presents an adaptive algorithm which can solve these problems, and it is based on orthogonal projection onto Multi-Demensional Subspace. This is an algorithm in which a parameter called overlap length which is based on orthogonal projection onto multi-dimensional space is introduced. This parameter can be set in compliance with the priorities of the problems mentioned above and can realize various operations forms including the conventional algorithms (e. g. Affine Projection Algorithm, Block Orthogonal Projection Algorithm). By choosing suitable overlap length, this algorithm can reduce the number of multiplications per sample time and it is possible to obtain fast convergence speed. Therefore, using the proposed algorithm, various operations can be supplied according to user's specifications. Affine Projection Algorithm and Block Orthogonal Projection Algorithm correspond to the special case of the proposed method. Finally, it is shown by computer simulations that the performances of the proposed method are very good and that it is useful for such applications as echo canceller, automatic equalizer etc.

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In this paper we propose a numerical computer method of the formal linearization for nonlinear systems. A nonlinear system is described by a system of nonlinear ordinary differential equations. A linearizing function is given by a sequence of the Chebyshev polynomials. It is required to be a solution of differential equations with nonlinear terms, which are represented by the method of Chebyshev interpolation. As a result, a formal linear system is derived from the given nonlinear system.
Numerical computation is easily carried out with the aid of computers. An algorithm and error bounds of the linearization are also included in the paper. Examples show that the accuracy of the method is improved as the order of the polynomials increases.

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To perform the effective application of plasma phenomena, the measurement of a radiation intensity distribution on an arbitrary internal cross-section is very important. We have already proposed “Light Emission Computed Tomography (LECT)” and succeeded in reconstructing a radiation intensity distribution. But very long data collection time is necessary to obtain the good reconstructed image by the conventional system. Therefore in order to reduce time for collecting the data, we have developed a new LECT system which uses a detector consisting of cylindrical lens and CCD device. And we have developed a new algorithm to reconstruct the tomographic layer. But when a discharge tube vessel is thick, the projection data in this system are degraded by refraction and reflection of rays on a discharge tube vessel. Therefore in this paper, we propose a method for obtaining high quality images using this LECT system. In this method, we perform the reconstruction with the consideration of the effect of the refraction and the reflection of rays upon the projection data. The experiments using the experimental system are performed to demonstrate the efficacy of this method and the experimental results are shown.

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