Abstract: A tube for a heat exchanger is constructed of a single plate having one end portion and the other end portion in a width direction perpendicular to a tube longitudinal direction. The single plate having opposite first and second wall surfaces is bent to have a protruding portion at a position adjacent to the one end portion in the width direction and a contact portion adjacent to the protruding portion in the width direction. The protruding portion is configured to continuously extend in the longitudinal direction and to have a protruding tip on a side of the first wall surface, and the protruding tip contacts the first wall surface of a portion along the longitudinal direction. The second wall surface at the one end portion and the contact portion contacts the first wall surface at the other end portion and a position near the other end portion, respectively.

Abstract: In a magnetic rotation angle sensor for detecting a rotation angle of a detection target, a yoke covers outer circumferences of a magnet and a Hall device. One of the magnet and the magnetic flux density detection device rotates together with the detection target. The Hall IC is radially shifted from a rotation center of the detection target. The magnetic flux density detection device has a detection surface that is in parallel to one of a tangential direction and a normal direction of a turning circle. The magnet is magnetized in the one of the tangential direction and the normal direction of the turning circle.

Abstract: In a magnetic rotation angle sensor for detecting a rotation angle of a detection target, a yoke covers outer circumferences of a magnet and a Hall device. One of the magnet and the magnetic flux density detection device rotates together with the detection target. The Hall IC is radially shifted from a rotation center of the detection target. The magnetic flux density detection device has a detection surface that is in parallel to one of a tangential direction and a normal direction of a turning circle. The magnet is magnetized in the one of the tangential direction and the normal direction of the turning circle.

Abstract: The absorbing rods have a nearly the same shape as the shape of columnar control rods for PWR used in reactivity control of core in a reactor. The absorbing rods can shield neutrons, and are inserted in control rod guide pipes and measuring pipes in fuel assemblies.

Abstract: A photoconductor which has an active layer including channels of ultrafine wire structures each having cross sectional lengths comparable to an electron de Broglie wavelength is provided. The photoconductor has a high gain and a considerably increased response speed. The electric current of the photoconductor may also be increased by introducing a superlattice structure.

Abstract: A field effect transistor comprises a gate electrode applied with a gate voltage, a channel forming region forming a channel in response to the gate voltage, and source and drain regions formed on both sides of the channel forming region, respectively, the channel forming region being made of a semiconductor material having an electron affinity which decreases as the distance from one surface thereof increases. The channel is formed at the surface of the channel forming region. An additional semiconductor material having an electron affinity lower than the electron affinity at the surface of the channel forming region may be interposed between the gate electrode and the channel forming region.

Abstract: For improvement in gate leakage current, there is disclosed a hetero-MIS gate type field effect transistor comprising (a) an indium-phosphide semi-insulating substrate, (b) an indium-phosphide active layer formed on a surface of the semi-insulating substrate, (c) an aluminum-gallium-arsenide layer formed on a surface of the indium-phosphide active layer, (d) a metal gate electrode formed on the aluminum-gallium-arsenide layer, and (e) source and drain electrodes formed on the indium-phosphide active layer and located at the both sides of the metal gate electrode, and the aluminum-gallium-arsenide layer has the highest aluminum atom composition at the upper surface portion contacting the metal gate electrode and the lowest aluminum atom composition at the lower surface portion contacting the indium-phosphide active layer, so that a discontinuity takes place between the indium-phosphide active layer and the aluminum-gallium-arsenide layer and a higher Schottky barrier is provided between the aluminum-gallium-ar

Abstract: A field-effect transistor comprises a semi-insulating InP substrate, a strained buffer layer of Al.sub.X Ga.sub.1-X As grown on the substrate, and an active layer of GaAs. The active layer is eased in regard to the influence of the lattice mismatching between the active layer and substrate. Such a field-effect transistor is associated with an optical device in a monolithic manner on a common semi-insulating InP substrate.

Abstract: A field effect transistor comprises a gate electrode applied with a gate voltage, a channel forming region forming a channel in response to the gate voltage, and source and drain regions formed on both sides of the channel forming region, respectively, the channel forming region being made of a semiconductor material having an electron affinity which decreases as the distance from one surface thereof increases. The channel is formed at the surface of the channel forming region. An additional semiconductor material having an electron affinity lower than the electron affinity at the surface of the channel forming region may be interposed between the gate electrode and the channel forming region.