For the modeling of power amplifiers (PAs) using sub-Nyquist-rate sampling (sub-sampling), a quadratic down-converting architecture with a parallel-cascade method is suggested. Its performance was analyzed regarding the sampling rate below the input Nyquist rate. As a result, the model from the sub-sampling below the input Nyquist rate characterized long-term memory effects whereas the memoryless model could not. The measurement results from RF PAs with the mWiMAX signal verified the modeling performance of this architecture. Also, for the modeling of memoryless PAs, it was shown that this sub-sampled model is still effective regardless of the sampling rate.

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In order to investigate the basic mechanical properties of a bias-type two-way shape memory component, thermal cyclic experiments were carried out on a TiNi shape memory alloy wire under a constant spring constant of a bias spring. The cyclic characteristics of recovery stress and recovery strain and the conditions for application of cyclic recovery stress and recovery strain were discussed. The main results can be summarized as follows. (1) The recovery stress and recovery strain induced in the two-way component take the maximum values at the initial strain near the completing point of the stress-induced martensitic transformation. (2) The recovery stress and the recovery strain decrease significantly in the early cycles, but take almost constant values after these cycles. (3) In order to obtain large recovery stress, it is necessary to make the spring constant of the bias spring high and to make the initial strain small. In order to get large recovery strain, it is necessary to make the spring constant low and the initial strain large. (4) The transformation temperatures of the stress-induced martensitic transformation and the reverse transformation rise with the number of thermal cycles. (5) In progress of thermal cycles, the stress-induced martensitic transformation and the reverse transformation occur gradually with variation in temperature, and the starting and completion temperatures of each transformation become unclear.

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Recent studies have proposed that there exist components of memory specific to each sensory modality for time perception. Moreover, several studies have suggested that memory for duration is more efficient and robust for visual stimuli than auditory stimuli, while a majority of studies reported auditory dominance over vision for temporal perception. The present study, using a time reproduction task with auditory, visual, and audio-visual stimuli, tested memory components by manipulating retention delays between the end of the target presentation and the beginning of reproduction. If vision dominates sensory specific memory for duration, performance with visual stimuli should be more accurate and stable under longer delays than performance in other modality conditions. Results showed that reproduced durations were longer and more unstable under longer delays than shorter delays in all modalities. Moreover, we found that auditory stimuli were reproduced more stably and for longer than visual stimuli. These findings did not support the existence of sense-modality specific memory components or visual dominance.

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For detecting potential problems of a cutter path, cutting force simulation in the NC milling process is necessary prior to actual machining. A milling operation is geometrically equivalent to a Boolean subtraction of the swept volume of a cutter moving along a path from a solid model representing the stock shape. In order to precisely estimate the cutting force, the subtraction operation must be executed for every small motion of the cutter. By using GPU, the required time for the subtraction can be drastically reduced. In this paper, the computation speed of two known GPU accelerated geometric milling simulation methods, which are the depth buffer based method and the parallel processing based method with CUDA language, are compared. Computational experiments show that the implementation with CUDA is several times faster than the depth buffer based method when the cutter motion in the simulation process is sufficiently small.

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電子部品を大量に使用するメカトロニクス機器では, 配線の合理化設計が必要である。ロボット・マニプレータでは, 手先部に多くのセンサやアクチュエータなどを搭載するため, それらの部品と制御器とを結ぶ大量のワイヤハーネスが存在し, これが将来のロボットの高機能化を考える上で, 重大な問題となる可能性がある。著者らの開発した自律分散型マニプレータでは, 関節ごとに計算機を組み込み, ロボット内ネットワークでそれらを結合することにより, 機器内部の配線削減を行っている。
本マニプレータは, 4自由度の関節部と6自由度の指部に高能力な制御用の組み込み計算機を有し, それらを結ブループネットワークを用いて, リアルタイムの動力学計算を実行することが可能である。
組み込み計算機は, 2台の16ビットマイクロプロセサと, ゲートアレイを用いた高速通信制御回路などから構成され, これらを4枚のハイブリッドICに集積化することで小型化を図っている。また, このハイブリッドICを搭載したジュラルミン基板を構造材や放熱器と一体化する形態としており, 総合的な高密度実装を考慮している。

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