Pulse fiber lasers have high beam quality and stability and are being used as industrial lasers. In recent years, pulse fiber lasers with higher power have been required for processing of difficult-to-cut materials and high speed processing. Accordingly, as one of methods for improving power of pulse fiber lasers, various systems based on coherent beam combining have been proposed. It is necessary for coherent beam combining that the optical phase and polarizations of individual beams to be combined are kept the same. Therefore, some system for adjusting them is needed.</p><p>In this paper, we propose a method for adjusting the optical phase of beams to be combined, by optical path length control in an all fiber coherent beam combining system which was developed through our past work. This system is one such that the optical phase and polarizations are kept the same by controlling only the optical phase because polarization changes are automatically compensated. We also confirm effectiveness of our method for controlling the optical phase through computer simulation.

We demonstrated a pup-up tag which is attached to fish and records action data for a fixed period. The tag is collected using the ARGOS system. The pop-up tag has an accelerometer, an angular velocity sensor and a pressure/temperature sensor. The characteristics of the accelerometer showed available performance from the relation between the acceleration and the angular velocity of turntable.

We propose a numerical method of frequency-weighted model reduction. The model to be reduced (an original model) is a stable SISO discrete-time model described by high-order state-space equations. We design the reduced-order model so that it can interpolate 1st- and 2nd-order information of the original model at complex frequency points (interpolation points) in the unit circle. The characteristics of the reduced-order model greatly depend on the choice of the interpolation points. The proposed model reduction method is a numerical one that chooses the interpolation points by searching in the unit circle to find the reduced-order model such that L-infinity-norm of the reduction error is less than a prescribed value. This method has the following features that show that it is an effective numerical method of the frequency-weighted model reduction, i) The reduced-order model is guaranteed to be stable. ii) The procedure for finding the reduced-order model is simple and requires a relatively small amount of computation. iii) The order of the reduced-order model can be controlled by choosing the number of interpolation points. (C) 1998 Scripta Technica, Electr Eng Jpn, 126(2): 31-39, 1999.

In this paper, we provide a model reduction method for stable MIMO linear discrete-time systems such that the reduced-order model interpolates a finite series of 1st-order information (information associated with the transfer function) and 2nd-order information (information associated with the power spectrum function) of the original system with respect to a direction. The directional interpolation approach to the model reduction guarantees the stability of the reduced-order model and can suppress the unnecessary increase of its order involved by the increase of interpolated information. We also propose an algorithm of the output frequency-weighted model reduction as an effective application of the model reduction via directional interpolation.

本書はUNIX・Linux に関する実用的な入門書である。対象は大学理工系学部の学生だが、他学部や高専の学生にも利用できるように、全体を基礎部分と応用部分とに大別している。基礎部分では、UNIXを学習するすべての学生に必要な事項であるファイルシステム、コマンド、シェル、ウィンドウ、エディタ、メール、シェルスクリプトについて解説している。応用部分では、文書作成(LaTex)、ホームページ作成(HTML)、プログラミング言語(C及びFORTRAN)、数理解析(Mathematica)、GUIプログラミング(Tcl/Tk)のような独立した章を用意しており、必要な章だけを選んで学習できるように構成している。

UNIXの操作方法、エディタの使い方、C言語のプログラミング、Tex、メール、Mathmaticaの使い方等、計算機実習に必要と考えられる分野の基礎部分を解説したテキスト。

安定な2次の離散時間システムに対してPI制御器を設計する一手法を与える。本手法では、部分的モデルマッチングで用いられる時間のスケールファクタを導入した離散時間参照モデルで制御仕様を表現し、制御系の特性が参照モデルの特性に一致するようにPI制御器を設計する。

オリジナルシステムの特定の周波数特性を保存するように低次元モデルを設計することは,モデル低次元化の有効な一手法である.本稿では,適当な複素周波数点において,オリジナルシステムの伝達関数の値およびパワースペクトラム関数の因果的部分の値を保存するモデル低次元化を考え,これらの値をそれぞれある方向に補間するような低次元モデルを与える.伝達特性とパワースペクトラム特性に関する情報をもとに補間することにより,低次元モデルの安定性が保証され,また,これらをある方向のみに補間することにより,低次元モデルの次数を制御することができる.