Abstract: A gas laser amplifier includes a housing, discharge electrode pairs, and an optical resonator. The housing includes an entrance window that allows entry of a first laser beam from outside and an exit window that allows exit of the first laser beam amplified. Each of the discharge electrode pairs excites a laser gas supplied between discharge electrodes facing each other in the housing. The optical resonator causes a second laser beam to oscillate with a gain of the excited laser gas in a non-incident state where the first laser beam from outside the housing does not enter the housing through the entrance window. In an incident state where the first laser beam enters the housing through the entrance window, the optical resonator suspends the oscillation of the second laser beam.

Abstract: An axial fan includes a hub having a rotation shaft and configured to be driven to rotate and blades provided to the hub. The blades each have a front edge portion and a rear edge portion. A first blade section is a section of a portion between the front edge portion and the rear edge portion of each of the blades along a direction in which the blades rotate, and the first blade section is an area of each of the blades that is further inward than an outer periphery edge portion that is a most radially outer periphery in each of the blades. In the first blade section, the blades each have a projection portion and a first recess portion. The projection portion projects from a portion of a pressure surface of each of the blades. The first recess portion recedes from a portion of the pressure surface that is between the projection portion and the rear edge portion.

Abstract: A ventilation control valve for a fuel tank is disposed in a ventilation passage which communicates an inside and an outside of a fuel tank. The ventilation control valve includes a float that floats on a liquid level of a fuel and moves up and down. The ventilation control valve includes a valve mechanism which switches a passage sectional area of the ventilation passage in conjunction with the float to an open state and a restricted state in which the passage sectional area is restricted from the opened state. The float has a volume chamber in which volume changes in accordance with a vertical movement of the float. A control gap as a flow rate adjusting mechanism is formed between the cylindrical wall of the float and the cylindrical wall of a case. Due to the control gap, the volume chamber functions as a damper.

Abstract: A ventilation control valve for a fuel tank is disposed in a ventilation passage which communicates an inside and an outside of a fuel tank. The ventilation control valve includes a float that floats on a liquid level of a fuel and moves up and down. The ventilation control valve includes a valve mechanism which switches a passage sectional area of the ventilation passage in conjunction with the float to an open state and a restricted state in which the passage sectional area is restricted from the opened state. The float has a volume chamber in which volume changes in accordance with a vertical movement of the float. A control gap as a flow rate adjusting mechanism is formed between the cylindrical wall of the float and the cylindrical wall of a case. Due to the control gap, the volume chamber functions as a damper.