Abstract: A method, circuit, audio playback device, and system of sending and receiving Bluetooth packet loss data is disclosed. The method includes: step S100, receiving a forwarding request sent by a second audio playback device in a receiving state; step S200, monitoring the retransmission information of an audio source device retransmitting current audio data on Link 1 according to the forwarding request; step S300, determining whether the retransmission information is monitored; step S400, switching from the receiving state to a sending state; and step S500, forwarding the current audio data to the second audio playback device through Link 2 in accordance with the time sequence of the audio source device retransmitting the current audio data. The signal can be provided to the second audio playback device from different locations.

Abstract: The present invention has an object to reduce residual stress in a tensile direction of a weld on the inner side in contact with reactor water of austenitic stainless steel piping, and to change the residual stress into compressive stress, to reduce stress corrosive cracking. The present invention provides a welding process for stainless steel piping of laminating two types of welding wire made of different materials in a groove of austenitic stainless steel piping, including at least one of a first layer penetration welding step of performing a predetermined back bead width on the back side of the groove bottom and a tack welding step, a first lamination welding step of lamination welding of austenitic stainless steel wire from the bottom to the top of the groove, and a second lamination welding step of lamination welding of nickel-base alloy wire to a final layer at the top of the groove.