Abstract: A heat exchanger includes: refrigerant channels that extend in a first direction, are disposed along a second direction intersecting with the first direction, and are disposed along a third direction intersecting with the first direction and the second direction; and heat transfer tubes defining the refrigerant channels. One or both of a size of an outer edge and a size of an inner edge of the heat transfer tubes are different between a first position and a second position in the first direction. Outer surfaces of the heat transfer tubes each include a protrusion that protrudes in a direction intersecting with the first direction, and is in contact with an outer surface of one of the heat transfer tubes adjacent thereto in the second direction. The protrusion includes a concave portion extending along the third direction.

Abstract: A coupler system includes: a coupler main body attached to a longitudinal direction end of a carbody of a railcar so as to be rotatable in a yaw direction; a curvature information acquiring portion configured to acquire curvature information of a track, the railcar being located on the track; a control portion configured to determine a target rotation angle of the coupler main body in accordance with the acquired curvature information and output a rotation signal regarding the determined target rotation angle; and a rotation angle changing portion configured to rotate the coupler main body to the target rotation angle based on the output rotation signal. When the railcar is stopped or when the railcar is traveling at a coupling speed, the control portion outputs the rotation signal to start rotating the coupler main body.

Abstract: A coupler system includes: a coupler main body attached to a longitudinal direction end of a carbody of a railcar so as to be rotatable in a yaw direction; a curvature information acquiring portion configured to acquire curvature information of a track, the railcar being located on the track; a control portion configured to determine a target rotation angle of the coupler main body in accordance with the acquired curvature information and output a rotation signal regarding the determined target rotation angle; and a rotation angle changing portion configured to rotate the coupler main body to the target rotation angle based on the output rotation signal. When the railcar is stopped or when the railcar is traveling at a coupling speed, the control portion outputs the rotation signal to start rotating the coupler main body.

Abstract: Biodegradable fibers of polylactic acid having a number-average molecular weight of from 50,000 to 150,000, have an interior portion having a higher alkali solubility than the exterior portion of the fiber. The fibers also have from 5 to 50 cracks/10 cm. The physical properties of these fibers are suitable for practical use, and the biodegradation of these fibers is controllable.

Abstract: Biodegradable fibers of polylactic acid having a number-average molecular weight of from 50,000 to 150,000, have an interior portion having a higher alkali solubility than the exterior portion of the fiber. The fibers also have from 5 to 50 cracks/10 cm. The physical properties of these fibers are suitable for practical use, and the biodegradation of these fibers is controllable.