筆者らの研究室では，以前，変調のパルスパターン改善法を提案した。この方法では，通常の変調法によりマトリックスコンバータのスイッチングパターンとデューティを求め，各出力相に接続する入力相の順番を並び替えたあとにキャリア比較することで，最終的なスイッチングパターンを決定する。すでに，この方法を用いて出力電圧ひずみの低減に成功したが，本論文では，入力電流ひずみを少なくする方法について検討し，シミュレーションによって通常の変調法との特性比較を行ったので報告する。

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This paper proposes a novel “Direct Space Vector PWM (Direct SVPWM)” strategy based on the direct AC/AC conversion approach for three-phase to three-phase matrix converters. This method allows the sine input and sine output waveforms as a major premise, and gives top priority to the improvement of the output control performance in motor drive applications, for instance, provides maximum riding comfort for an elevator, etc. Output voltage harmonics, switching losses, and common-mode voltage can be reduced across the entire voltage region. In addition, the switching count can be reduced even further by fully utilizing the output current detection value.
Direct space vectors are first defined, and the selection method of space vectors is described. Next, the PWM duty calculation technique is explained. Finally, the validity of the proposed method is proven from the comparison with the conventional virtual indirect method based on the experimental and analysis results.

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Characteristics of the spatial VCG was examined for the purpose of application to automatic diagnosis of the ECG. The analysis aimed at improvement of the diagnostic logics and parameters reported previously. Spatial VCG data series were obtained by the same procedure and analysed by the same on-line system as reported previously.
The relationship between the time interval of the beginning of QRS vector to the maximum magnitude vector and that of the maximum magnitude vector to the end of QRS vector was very effective for differential diagnosis of intraventricular conduction disturbances.
It was confirmed by frequency distribution of maximum QRS vectors that many false positive cases were included in the cases with left ventricular hypertrophy diagnosed by the conventional ECG lead system. Polar vector of an approximated plane of the initial QRS vectors was an useful parameter in diagnosing anterior myocaldial infarction. If an increase in the included angle between the maximum vectors of QRS and T is attended with an increase in the included angle between polar vectors of those planes, myocardial damage will be certainly diagnosed. Planarity of an approximated plane was represented by RMS of angles between instantaneous vectors and a plane. It was inevitably favorable in normal QRS vector.
Coordinate of the lead axes was transformed to patient's own heart axes. New coordinate was framed by maximum magnitude vector (X), polar vector (Y), and orientation at the right angle to both the former two (Z). Another attempt was made to establish the magnitude normalized VCG, whereby orientation of the spatial vector was extracted. An accurate pattern recognition of the spatial vector loop was successfully performed by the above procedure, because the electrical orientation of the heart displayed in a patient's peculiar frame was independent of anatomical heart position.

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マトリックスコンバータは，商用三相交流電圧を振幅可変，周波数可変の交流電圧に直接変換する変換器である。マトリックスコンバータは，従来の整流器－インバータシステムと比較して，大容量電解コンデンサを必要とせず変換器の小形化，長寿命化が可能であることから注目されている。本論文では，筆者らが先に提案したパルスパターン改善変調方式を用いてシミュレーションと実験を行い，提案方式において使用されるの種類が，出力電圧指令値の大きさに応じて自動的に変化していく過程を確認したので報告する。

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This paper proposed a space vector modulation method to reduce the input current harmonics of a matrix converter. In the proposed method, the input current harmonics were defined in order to evaluate the input current THD of each modulation rate, power factor and phase of the input and output. Switching patterns minimizing the input current harmonics and distribution of the input current harmonics were shown by visualizing in the space vector. The proposed space vector modulation method clarified the effectiveness of the input current harmonics reduction by simulations and showed the 40-point reduction of the input current THD as compared with the conventional method.

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マトリックスコンバータは，商用三相交流電圧を振幅可変，周波数可変の交流電圧に直接変換する変換器であり，従来の整流回路–インバータのシステムに比べて，効率，EMI，小型軽量化可能等の点で優れていることから盛んに研究が行われている。本論文では，筆者らが先に提案したパルスパターン改善変調方式についてシミュレーションにより検討を行い，提案の変調方式を用いれば，出力電圧指令値の大きさに応じて，使用されるの種類が自動的かつシームレスに切り替えられることにより，出力電圧ひずみが低減されることを明らかにしたので報告する。

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A multi-level inverter has potential advantages in high blocking voltages and reduced harmonics. However, it has a technically challenging subject that the DC input voltages must be balanced. This paper proposes and investigates a new double-mapping-based space-vector modulation (SVM) method to solve the subject without any additional circuit. The proposed method consists of two steps. One is the SV map data generation for the five-level NPC inverter based on a general principle to utilize redundant SVs. The other is the optimal selection of the SV pattern which balances the the DC input voltages based on the double-mapping-based SVM method which has two different kind of control schemes for low and high modulation indexes. The proposed method is investigated and validated through simulated results by a digital control system.

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The purpose of the present study is to clarify the origins of auditory brain stem responses. We recorded the auditory brain stem responses by three ortho-diagonal leads (X-axis; right ear lobe to left ear lobe, Y-axis; vertex to submental, Z-axis; forehead to inion). We studied the wave-forms on each three plane, frontal, sagittal and horizontal, and analysed their vectors on the basis of Lissajous' figure. Lissajous' figures revealed the following facts.
1) Vector of N₁ is almost horizontal and directs toward the non-stimulated side.
2) N₂ seems to be derived from the double firings of the auditory nevers and cochlear nuclei.
3) Origins of N₃ are the activities of the circuits of the auditory pathways in the brain stem.
4) Vector of N₅ is the largest of five responses, and directs toward the fronto-parietal region, tilting slightly to the non-stimulated side.

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This paper proposes an isolated DC/AC converter that has a small inductor and capacitor. In the proposed converter, an active power decoupling circuit is applied to a synchronous rectifier, which can compensate for the double-line frequency ripple of single-phase AC grid using a small capacitor. In addition, the proposed converter can achieve zero current switching using pulse density modulation (PDM). From the experimental result, the second-order harmonics of the input voltage is reduced to 2% in comparison to the DC components. In addition, the inverter output current THD of 2.2% is achieved.

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This Paper proposes a novel conversion scheme of switching patterns for three-phase to three-phase matrix converters. The conventional virtual indirect conversion method is equivalent to PWM technique via an ordinary PWM rectifier/inverter, offering the advantage that no complicated specialized control is required. On the other hand, 6 of 27 switching patterns cannot be used in this method, because the inputs and outputs are always connected by way of the virtual DC link that is composed of 2 lines. This paper therefore defines the direct space vectors that can express the all 27 switching patterns and utilizes the geometric relationship of direct space vectors so that all switching patterns can be converted from other arbitrary vectors. This conversion scheme also allows the duty factor conversion with simple calculation by utilizing the duties of the virtual indirect conversion approach. In particular, the above-mentioned 6 switching patterns that have been restricted can be fully utilized for reducing output voltage harmonics, switching losses and common-mode voltages. The validity of the proposed conversion method is proven from the experimental results compared with a conventional virtual indirect method.

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We have developed a pixel interpolation method for digital cameras, that uses the correlation between the primary colors. And we improved this method by combination with average method in high saturation area and pixel selection in area which contains an edge. The simulation showed that this interpolation method is more distinct than interpolation only by average method.

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隣接画素ブロックのパターン情報を基とした単板式ディジタル電子カメラへの画素補間方式を提案する.画像信号におけるR, G, Bのパターン的高相関性と, 角度空間展開による正確なパターン識別を利用して実現する.本論文では, シミュレーション実験によりその有効性を示す.

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In the product planning procedure of machine tools, mature designers always analyze and consider various customer's requirements and also conduct necessary information processing so as to obtain the most suitable product specifications. In order to rationally systematize such a procedure, it is necessary and indispensable to analyze and establish the decision making in the product planning of machine tools. Thus, in this paper, a product evaluation method using customer satisfaction degree has been proposed to establish a product development methodology for machine tools. The validity and effectiveness of the proposed evaluation method are verified through some case studies.

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