本研究では,エンジンの動作する原理を,コンピュータグラフィックス(CG)アニメーションを用いることで,各構成部品の働きを,動きの中で有機的に結びつけて示し,効率よく学習させるマルチメディアコンテンツを開発した.本コンテンツを機械工学科1年生の機械実習実験科目で行われる「エンジンの分解・組み立て実習」の授業において実践し,学生に対して行った小テストおよびアンケートの結果からその学習効果について検討を行った.その結果,本コンテンツはエンジンの動作メカニズムを理解させる教育支援コンテンツとして有効であることを確認した.

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A piezoelectric bimorph element is useful for a slip sensor for robots because it is sensitive to dynamic stress, can be made small and its signal circuit is simple. A slip sensor using a piezoelectric bimorph element presented in this paper detects the first large pulse caused by frictional slip and also detects the instants of both contact with and release from an object. However, since it is easily influenced by vibrations transmitted from robot actuators and other sources, this slip sensor requires a vibration absorber at its supporting point. Therefore, experiments on motions of touch, slip and release were performed after reducing vibratory noise by means of an absorber at a foot of the device. It was found that the slip sensor reliably produces one pulse at the instant of first slip, and also produces one pulse at the instant of contact with or release from an object. The release signal is opposite to the touch one.

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  In the past paper the authors developed the design method for determining the gains of PID controller of Smart Helmholtz Resonator by using Response Surface Method and optimization analysis. This method is the original method by the authors and the details are described in the authors' papers. There, it was concluded that the desired resonance frequency of the resonator can be obtained quite accurately by using the gains from the analysis. However, it was shown that there is the error due to the optimization analysis from error analysis. When using optimization analysis, accuracy and calculation cost become key problems. In order to improve this fact it is needed to develop the more accurate method. In this paper it is proposed to utilize Artificial Neural Network (ANN) to improve the accuracy of the obtained resonance frequency. From the numerical simulation it is confirmed that the mapping between the integral gain K_I and the resonance frequency can be constructed very well by using Holographic Neural Network(HNN) and the accuracy of the testing is improved by selecting the input and output of the HNN properly. Namely, the mapping between a single input variable and multiple output variables cannot be constructed correctly, so the mapping between a single input variable and a single output variable is adopted. Moreover, it is found that the relationship between the resonance frequency of the resonator and the integral gain of PID controller is linear under the certain condition by doing simulation. And it is confirmed that the smart Helmholtz resonator is stable in the frequency range adopted in this simulation.

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  In a coupled structural-acoustic system which has a box structure and interior air the position of a defect included in the structure is identified by using the frequency response of sound pressure level in the interior sound field. For the analysis of coupled structural-acoustic system Finite Element Method (FEM) is utilized. The box including a defect is excited by dynamical load and the frequency response of the interior sound are learned by Self-organizing Maps (SOM) as an input vector and the map is drawn in the 2-dimensional plane. The frequency response for the model whose defect position is not known is given to the trained map, and the identification is carried out. As a result the good accuracy of the identification is obtained. Furthermore, it is confirmed that the identification by SOM is better than by the other neural network such as LVQ (Learning Vector Quantization) or BNN (Back Propagation Neural Network).

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Some recognition methods were compared with in this paper for characteristic signals of hand waving gestures. Confused motions between "beck" and "driving away" were distinguished by each characteristic signal, mixing with a gravity motion and an area variation of the image of a moving hand. Therefore their dynamic gestures were able to recognize by methods of DP matching, wave difference and others. The results are the following : (1) taking the difference of a hand waving trajectory, the recognition ratio rose to more than 92.3%, (2) DP matching was not so available in the formless motions, (3) but by using some categorized vectors to search the same vectors in a trajectory, it was cleared that the miss-recognition between "beck" and "driving away" is sup-pressed.

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To determine the quantities affecting electroviscous effects, we studied the change of the effects due to the electric field, shear stress, volume concentration of powder and kinds of aluminum powder and turbineoil. As a result, it was found that the electroviscous effects was controlled by the non-dimensional parameter expressing the ratio of the force acting on the conductor per unit area in the electric field and the shear stress when no electric field was applied. The effects increased almost linearly with the increase of the non-dimensional quantity. The slope increased as volume-concentration of aluminum powder increased. The slope changed with the kind of alminum powder. As the grain diameter became larger, the slope increased, and a higher slope was obtained with flaky powder than with granular or acicular powder.

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低温で水酸アパタイトを合成するため、数種類の炭酸カルシウム粉末と方解石をリン酸水素二アンモニウムと反応させた。粉末の炭酸カルシウムでは、40℃で4時間反応後にアパタイトが生成した。方解石の場合では、表面上に生成物が観察されたがその生成物を同定するのは困難であった。

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La_0.6Sr_0.4MnO₃の組成の複合マンガン酸化物に酸化物SiO₂、V₂O₅、Bi₂O₃またはCuOをモル比でLa_0.6Sr_0.4MnO₃:MO_x=100:8(MO_xは添加した酸化物)となるよう添加したセラミックスを作製した。SrやLaを含む不純物が生成し、組成変動が考えられた。電気抵抗率は無添加試料が最も高く、SiO₂、CuO、V₂O₅、Bi₂O₃添加試料の順に急激に低下した。無添加試料ではT_c付近で磁気抵抗は僅かな極大を示し、CuO添加試料も同様であった。それ以外の添加試料ではそれらのT_c付近で明瞭に極大値を示した。これら磁気伝導特性の変化は添加に伴う組成変動だけではなく、微細構造の変化にも由来すると予想された。

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For clarification of grasping mechanisms of handles and hafts, ensory evaluation of the optimum diameter and measurement of the grasping forces of fingers during the sensory evaluation and during holding of a weight were performed for various grasping methods. It was clarified that the optimum diameter of pipe to be grasped depends on grasping methods, i.e. on which finger principally holds the pipe. Moreover, in this study a pipe of optimum diameter was grasped using mainly the middle finger with no restriction of grasping method. We found that the fingers grasping the pipe of optimum diameter are able to produce a maximum grasping force and are able to hold a maximum amount of weight.

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In order to clarify the grasping mechanism of tools and handles, sensory tests have been performed and bio-measurements, i.e. electromyograms and measurements of finger forces, have been recorded. Feeling of the optimum diameter for holding cylinders had learning effect within 20 minutes; that is, the diameter increased after long-time grasping of the larger cylinder, while it decreased after long time grasping of the smaller cylinder. It was found that the optimum diameter determined by the sensory tests was that for long-time holding with reduced muscle fatigue and strong grasping force.

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In this paper we carried out the simulation for controlling the resonance frequency of a Helmholtz resonator, which is used for the reduction of noise. The resonance frequency is designed to the desired value by PID control of the acoustical boundary condition of the Helmholtz resonator. The resonator like this is called Smart Helmholtz Resonator. At first the gains of PID controller is changed to several values and it is confirmed that the resonance frequency is varied. In order to realize the desired resonance frequency the gains of PID controller are determined by the response surface method. By using the response surface method the determination of the optimal gains are possible for a lower frequency region quite accurately. It is shown that this method is effective for designing the resonance frequency of Smart Helmholtz Resonator.

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特別企画 「学生教育・生涯教育に思うこと」 対談

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In 2010, Kanagawa Institute of Technology started the Aerospace Course in the department of the mechanical engineering. In this course, the flight simulator is used not only for the pilot training but also for the purpose of supporting the understanding of the flight dynamics. In this study, a stereoscopic flight simulator which assists the learning of flight dynamics was developed. The educational effectiveness of the flight simulator was examined by questionnaire. The analysis of questionnaire showed that the stereoscopic flight simulator was not so effective for the understandings of the flight dynamics, but showed that the flight simulator raised the learning morale of the flight dynamics.

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