Simplification of the Iron Ball Magnetic Levitation Equipment

We have previously reported on improving the equipment by which an iron ball was made to float using a magnet, along with adjustment of the position of magnet and iron ball. As a result, the time required to achieve floating was greatly reduced. In this study we report on lightening the equipment and simplifying the operation. Through trial and error we were able to float a ball of about 50 g gross mass. And, it was possible through simple operations to make the iron ball float in a short time (few seconds).departmental bulletin pape

On the generation of the torque in a ball bearing motor

We examined the generation of torque in a ball bearing motor from the electromagnetic viewpoint, i.e., the possibility that the torque was generated by current in the metal spheres. We noticed that a repulsive force between the conductors was generated by the magnetizing currents, if the conductors were close to each other. Based on this fact, we examined the current route in the motor. As a result, we noticed that the current direction into the spheres and out of the spheres is in the opposite direction as each contact between the outer ring and the metal sphere, and the metal sphere and the inner ring of the bearing was passed, i.e., the contact is made at a boundary, and the current direction in the inner ring is opposite to that in the outer ring. From this fact, a repulsive force due to the magnetizing current occurs between the conductors which form each contact, and we took this force as the origin of the torque in this motor. The factor which determines the direction of rotation coincides with the non-directional rotational characteristic of this motor, because it is not included in the generation of this repulsive force. Simply put, the motor rotates in either direction.departmental bulletin pape

Three-dimensional magnetic field observation vessel using magnetic fluid

In this study, an observation vessel which could depict magnetic field distributions in three dimensions was produced. The magnetic field observation vessel was made by putting magnetic fluid and water in a transparent square shaped glass container. Observation of both permanent magnet and electromagnets was carried out. The movement of the magnetic fluid is different depending on the placement of the magnetic poles. The magnetic fluid showed a tendency to gather near each magnetic pole, when it was placed between the same magnetic poles placed face to face. On the other hand, the magnetic fluid collected between the two magnetic poles, when it was placed between different magnetic poles placed face to face. In most magnetic field observation devices, such observation is difficult. The results indicate that the magnetic observation vessel is useful in explaining the relationship between magnetic lines of force and magnetic force.departmental bulletin pape

The development of teaching material using an experiment to produce cognitive disharmony

It is generally accepted that a repulsive force exists between homopolar magnets. We have, however, encountered a process that is different from the generally accepted repulsive force and use this phenomenon in a teaching experiment that illustrates cognitive disharmony. The repulsive force acts between homopolar magnets only when the difference in magnetic flux density between magnets is roughly equivalent. And this repulsive force changes depending on the distance between the magnets. On the other hand, the force which acts with decreasing distance between magnets, changes from a repulsive force to an attractive one when the difference in magnetic flux density between the magnets is large (one magnet several times stronger than the other). A decrease in the magnetic flux density and reversal of polarity appears in the magnet where the magnetic flux density is lowest. It is clear that the force which acts between magnets changes from repulsion to attraction or vice versa for separations of 1 mm or less. The experimental results confirmed this phenomenon as an effective teaching tool, especially for teaching how to handle cognitive disharmony.departmental bulletin pape

Verification of the magnetic force in a finite length magnet

The force which acts between two magnets is different for the infinite magnet set of poles. In the case of the finite length magnet there are four forces (F1, F2, F3, F4), because there are four pole faces in the two magnet (A,B), i.e. (1) Force F1 which works in front of magnet A and in the front of magnet B, (2) Force F2=F3 which affects front (rear face) of magnet A and rear face ( the front ) of magnet B, (3) Force F4 which works in rear face of magnet A and in the rear face of magnet B. The force which acts between the magnets is the sum of these forces (F0=F1+F2+F3+F4). In this study, the relationship, for the same magnetic pole, between distance between magnets and force was examined in order to verify this sum of forces relationship. We compared measured values to calculated values. The measured F0 characteristic tended to be similar to the F(∝ 1/r0 2 , r0 is the distance between magnetic centrals ) characteristic. The difference between F and F0 is a way of the definition of the distance.departmental bulletin pape

中村先生のご退職にあたって

othe

KEY ASPECTS FOR TAKING PARTICIPATORY APPROACHES IN RESEARCH, PROGRAM DESIGN AND INSTITUTION MANAGEMENT

参加型アプローチとは何だろう。米国、インドでの経験を元に筆者が考える研究者側から捉えた参加型アプローチの心得をまとめてみた。内容は三部構成になっており、最初に地域調査、次にプログラムの計画、そして最後に組織の運営についての参加型アプローチを論ずる。地域調査の項目では人材の選択、研究者の専門分野の多様性、地域住民の参加、問題定義のあり方、そしてコミュニケーションの必要性について述べていく。プログラム計画の項目では参加型アプローチを取り入れた教育カリキュラムと教授法について考える。地域に根ざした、学習者の意向を尊重したカリキュラムの作成法、実践的な学習のあり方、学習環境、そして学習者中心の教授法について考察していく。最後に組織の運営について、このケースでは教育機関もしくは学校経営に参加型アプローチを取り入れてみる。どのような人材がどのような役割を持つのか、その際地域住民の参加の度合いはどのように処理されるのか、そして運営上の計画、実践、評価の過程がどのようにとらわれるのか、教育機関にラーニングオーガナイゼーションの特徴を取り入れて論じていく。教育政革に少しでも貢献できればと思い記述してみた。departmental bulletin pape

死因贈与における受贈者の先死と民法九九四条一項の準用の有無

Articledepartmental bulletin pape

ジャワにおける病と生活環境の変化―19世紀初頭から20世紀初頭―

Article【論文／Article】departmental bulletin pape

The development of the power generation experiment vessel using the stator of the electric fan

扇風機に使われている誘導電動機の固定子を使った発電実験器を開発した．誘導電動機の固定子には回転磁界を作るための複数のコイルを回転磁界用と発電用に分けることを考えた．発電させるために，回転子の代わりに球形磁石を用いた結果、磁石による発電現象が確認できた．電動機の部分と発電機の部分の両方を有する発電実験器を得ることができた． The power generation experiment vessel using the stator of the induction motor used in electric fan was developed. In the stator of the induction motor, it was considered that multiple coils for making the rotating magnetic field were divided for rotating magnetic field and power generation. The power generation phenomenon by the magnet was able to be confirmed as a result of using the spherical magnet instead of the rotor in order to generate electricity. It was possible to obtain the power generation experiment vessel with both of part of the motor and part of the generator.departmental bulletin pape