We have been investigating several technical measures to improve hydraulic performance of pump-turbines which are to be installed into pumped storage power stations with a wide operating-head-range. A splitter runner, which has long blades. and short blades in circumferentially alternate positions, can be one of the means for achieving this aim. In this paper, characteristic flow-patterns in the splitter runner and appropriate design methods based on them are discussed. As far as flowpattern is concerned, influence of circumferential pitch between a long blade and a short blade is focused on especially. Through flow analyses for some runners, it has become clear that making the short blade move to its pressure side direction enhances turbine operation performance. After optimization of the runner by flow analysis at the design stage, model tests were conducted to verify its hydraulic performance and to optimize it further. Finally, the developed splitter runners for low/high specific-speed pump-turbines proved to demonstrate better hydraulic performance and smaller pressure fluctuation compared to conventional runners.

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ダクト騒音対策の一つとして,矩形ダクト内部にを設ける消音法がある。音の伝ぱ経路差を利用した干渉形消音器であり,平面波に対してはダクト曲がり部に設けるコーナベーン方式となる。しかし伝ぱ音が高次モード波であれば,ダクト断面の音圧が一様でないため,ダクト直線部に設けた直線状においても消音効果が得られる可能性がある。本研究ではFig.A1のx方向1次モード波について,の長さと挿入位置を種々変化させた場合の音の透過損失を測定し,消音周波数と音の低減量をまとめる。Fig.A1のy方向に音場は一様であり,の特性はl, a, hで定まる。hを基準寸法とし,波数kによる無次元周波数khを用いる。1次モード波の伝ぱ特性を正確に測定できる実験装置を用いて,での透過損失の周波数変化を調べる。測定範囲はπ<kh<2πである。この範囲内で,を設けることによって透過側に平面波が生じることはなかった。Fig.A2は透過損失曲線の一例である。透過損失が極大値TL_<MAX>を取る周波数を干渉周波数kh_Iとする。特性は寸法によって変化し,それぞれ2つの干渉周波数が存在する。低周波側から順に1次,2次と呼ぶことにする。Fig.A3には,条件に対する干渉周波数(1次,2次)の変化をまとめた。が長く,ダクト壁に近いほど,kh_Iは概ね小さくなる傾向を示す。しかし,この傾向に反する場合もあり,kh_Iの変化は単純なものではない。Fig.A4には,条件に対する最大透過損失の変化をまとめた。図が煩雑になるのを避けるため,1次での値のみ示す。全体的には,が長いほどTL_<MAX>は大きくなる。また,ダクト中心とダクト壁との中間付近(a/h=0.2もしくは0.3)にを置けばTL_<MAX>は大きくなる。ただし,が長いときの消音効果は,がダクト壁に近いほうが大きくなる傾向にある。平板を1枚挿入するだけの単純な方法で,最大30dB程度の効果が得られるが,上記のとおり,現象の特性把握はなかなか難しい。モード波はz方向波長が周波数依存し,xy面内での音圧変化もあるので,複雑な特性を示す。現在,有限差分法を用いた数値計算によって実験とほぼ同等の結果を得るに至っているので,今後は計算によるダクト内音場理解を進めていく予定である。

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Mechanism of flow induced vibration of a circular cylinder with a splitter plate was investigated by flow visualization techenique using the smoke wire method. When the distance between the cylinder and the splitter plate is within some 2.5 diameter of the cylinder, the shear layer of the stationary cylinder reattachs on the plate not to form the reqular vortex. On the other hand, the shear layer of the vibration cylinder is always rolled up reqularly synchrounously with the vibration even when it reattachs on the plate. When the distance is 1.5 diameter, the strong vortex sheds into the wake by the interaction of the rolling up of the shear layer and the edge of the plate, then the strong flow induced vibration is induced.

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We have developed a 2-D/3-D compatible display without special glasses. We set the image-splitter between the LC panel and the backlight in order to achieve the 3-D images without special glasses. We set a controllable scattering shutter between the LC panel and the backlight in order to display not only 3-D images without special glasses but also normal 2-D images without losing the resolution of the LC panel. By controlling both the image and the special shutter, a 3-D image and a 2-D image can be created in any rectangle groups of 16 rectangles on the screen. A 2-D image can also be viewed without losing resolution. Furthermore, this display has a 3-D indicator to make it easier to find the proper viewing area without the special glasses. We applied these technologies to a 3-D system on the Internet.

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This paper presents the development of a low specific speed Francis turbine runner. In order to achieve the improvements of cavitation performance and turbine efficiency throughout a wide operating range, a new runner design method that combines the latest Computational Fluid Dynamics (CFD) and a multi objective optimization design with an existing design system, was applied in this study. The validity of the new design system was evaluated by model performance tests. As the results, it was confirmed that the optimized runner presented better anti-cavitation performance and higher turbine efficiency compared with a conventional design runner.

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本研究グループでは、歯根管治療への応用を目指したイメージファイバ観察システムを開発している。試作したシステムに関して、現状では照明光をビームーを介してイメージファイバに導入する際に、ビームーの壁面で反射した光が観察用CCDへ映り込み、取得画像が不鮮明になるという問題点が判明している。本研究ではこの問題を解決するために、光源から出た光に対し、遮光マスクを集光レンズ上の中央に設置し、リング形状の光をビームーに導入する方式を考案した。この手法により、リング状の反射光だけがCCD鏡筒の絞りで遮られ、観察画像は絞り中央部を通過し、鮮明な画像を得ることに成功した。

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メガネなし立体ディスプレイの多くは，観察者が観察領域からずれるとクロストークや逆視が生じるため観察者は限られた位置でしか立体視することができなかった．最近では観察者トラッキングと組み合わせることで逆視をなくしたり，運動視差の再現ができるようになったりしたが，一人にしか対応できないという問題があった．そこで本稿では，パララックスバリア方式において三視差を用いた画像表示で二人の観察者に対応できるトラッキング型立体ディスプレイを提案する．提案システムでは，観察位置に応じた二つの画像表示方式があり，試作システムを用いた実験により二人の観察者は常に逆視のない立体視が可能となることを確認した．

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ビームーとミラーを一体化した光学素子を開発し、オフアクシス型のシアリング型硬Ｘ線結像顕微法の実現可能性について調べた。ドライエッチング技術により、厚さ約 0.5 μm のビームーとミラーを同一シリコン基板上に作製した。Ｘ線イメージングの実験は 9 keV の単色Ｘ線により行った。ビームーの反射Ｘ線と透過Ｘ線の強度のバランス、形状精度などの問題から、干渉像を得るには至らなかったが、今後、本研究を進める上での課題と限界が明らかになった。

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The authers have systematically analaized the reattached jet flow in a wall reattachment fluidic device by means of experiments and theories which are fluid-dynamically reasonable, though may not be rigorous.
From a view point of the design of wall reattachment device, we begin with the summary of our results obtained. Then, discussing the possibility of a direct design in the sense that it is independent of an experimental trial and error, we make clear some points to be further investigated. Finally, it is shown that the device is directly designable when some important quantities of static characteristics are given as the performance indexes.

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In this study, experiments in two intersecting ducts with a circular perforated zone are performed to investigate secondary flow and mixing in the perforated zone when changing the conditions of the intersecting angles and the upper water levels. The flow pattern in the perforated zone is visualized by the particle tracing method and the LDV. The flow rates in the downstream ducts are measured by hydrometry. Colorimeters, which have been used with color video images to analyze the visual field of complicated scenes, such as landscapes and building interiors, are used here to examine mixing. The characteristics of the secondary flow, the resistance and the mixing process in the perforated zone are clarified.

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In Ocean development, many cylindrical shape structures are in use. These structures are subjected to many external forces, such as water current, waves and reaction force from the upper structure. Especially, the lift force induced by the shedding vortices cause the vibration of the structures. This phenomenon is called Vortex Induced Vibration, VIV. It is assumed that VIV causes fatigue damages on the structure because it contains high frequency component of vibration and it increases in drag force on the structure.One of the solutions to decrease VIV, the appendage such as splitter plates or fairings is used to be attached on the structures.However, it may happen that such appendages increase the amplitude of VIV in some situations. Meanwhile, for actual use, it must be considered not only the decreasing performance but also the ease of handling. If we use Computational Fluid Dynamics, it is easy to modify the shape of the appendage and simulate its performance in different circumstances. Before that, it is needed to reveal the influence of the motion and flow field around the structure with the appendages.In this study, a rigid circular cylinder with or without appendage was supported by coil springs in the circular tank. The motion and rotation of the cylinder were measured by tracking the markers attached on its cross section. In the same manner, those of the appendage were also measured. The flow field around the cylinder was visualized by PIV. Experimental results show that the appendage, such as splitter plate or fairing, sometimes can’t decrease the amplitude of VIV. They also show that the appendage which can shorten the distance between the shedding vortices near the cylinder can decrease VIV.

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This paper describes a function of a splitter on flow mechanism of a switching of jet in a wall-attachment fluid amplifier.
A very simplified device was used as an experimental model and the switching mechanism in it was studied by visualizing the flow using a motion picture and by measuring pressure distributions on walls.
The mechanism of the interaction between jet and splitter was analyzed. An attachment distance, an amount of switching flow, and switching time period in the switching process were calculated from the simulation model derived from experiments. It was found that both the initial attachment distance and an amount of switching flow were varied with splitter position, since the low pressure distribution nearby the tip of the splitter eased the jet curvature. The switching of jet was restrained due to the low pressure distribution caused by the separation of streamline at the tip of the splitter in the output duct.

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We have newly developed two types of 15" high resolution non-glasses 3-D displays, the one is no cross-talk 3-D display using the double image splitter technology and the other is 2-D/3-D full compatible display using the image splitter and the controllable scattering shutter technology. In this time, in the 2-D/3-D full compatible display, controllable scattering shutter is united with image splitter in order to realize simple construction and short viewing distance of the non-glasses 3-D image. Those displays adopted newly developed head tracking system. The head tracking system detects the viewer's head position without special attachment and adjusts the images automatically. So it can expands the stereoscopic area. With this combination of larger screen, higher resolution and head tracking system, the display enables viewer to have more realistic and enjoyable images.

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メガネなし立体ディスプレイの多くは，観察位置が観察領域からずれると，クロストークや逆視が生じるため観察者は定められた位置でしか立体視することができない問題がある．このため，観察者の視点位置を2台のカメラを用いたステレオシステムで計測し，観察者を追尾する立体ディスプレイが多数提案されている．本論文はカメラ1台とそのカメラの視域を制御する鏡2枚を使用する観察者の視点位置計測システムを提案する．このシステムには，視域制御鏡の設定は精密な位置合わせが必要なく，視角はカメラ2台のシステムの3/4を有し，ステレオ計測の同期問題にも対応できるなどの特徴がある．

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We have developed an optical system using three D-ILA^TM (Direct image Light Amplifier) panel modules (reflective type liquid crystal device) for a projection display that produces extra-bright, high-resolution, images having high contrast ratio and good color reproduction. It uses some dichroic mirrors for color separation and one cross dichroic prism for color combination. The polarizing performance of these optical elements enables it to achieve such good color reproduction.

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For a long time, people have kept looking still pictures and movies as plane images. And they take it for granted up until now. But demand for watching every kind of objects as 3D image through monitor is increasing.
We have researched on 3D image technology for more than a decade, and this time we developed two kinds of 3D displays. One is the stereo type display using Image-Splitter method and the other is the multi view type. The advantage of them is that we don't have to wear special glasses to see 3D images.
We introduce these 3D displays below, which is expected to be a future 3D-TV set because of their simple structures.

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