Abstract: This application discloses a NB-IoT-based communication method and an apparatus, to evolve a NB-IoT communication technology into an NTN. The method is as follows: A terminal device generates an uplink signal, including a superframe which includes a synchronization sequence located in first duration of the superframe and a data frame located in second duration which is after the first duration, the synchronization sequence successively includes a first sequence repeated Ni times and a second sequence repeated N2 times, the second sequence is obtained by multiplying the first sequence by ?1, a part of consecutive sequences of the synchronization sequence are used as a first synchronization reference sequence that is obtained based on the second sequence repeated N2 times and one or more first sequences that are sorted from back to front in the first sequence repeated N1 times. The terminal device sends the uplink signal to a network device.

Abstract: A partitioned lifting forming type selective laser melting workbench, comprises at least forming platform (1) for powder-spreading and sintering and forming of workpiece, the forming platform (1) comprises forming inner abutment (1-1) and at least one forming outer abutment (1-2) which is sleeved on the forming inner abutment (1-1) and arranged in sequence from the inside to the outside in a radial direction, the forming inner abutment (1-1) and each forming outer abutment (1-2) are arranged in a manner of rise and fall, the forming inner abutment (1-1) or the forming outer abutment (1-2) falls independently, or the forming outer abutment (1-2) and the adjacent forming outer abutment or/and the forming inner abutment (1-1) fall together, it can form an area (2) to be subjected to powder-spreading for laser sintering and forming of workpiece.

Abstract: A efficient large-scale selective laser melting forming device comprises a rack (1), a forming workbench (2) arranged on the rack, a forming bin (3) sleeved on the forming workbench and a galvanometer scanning device (7) arranged outside the forming bin and moving reciprocally along the powder spreading direction to form a multi-station working state, and a smoke blowing and sucking mechanism (8) arranged in the forming bin in a mode of synchronously moving to the same station with the galvanometer scanning device. The galvanometer scanning device can move reciprocally along the powder spreading direction to form a multi-station working state. The galvanometer scanning device is entirely arranged outside the forming bin. The smoke blowing and sucking mechanism arranged in the forming bin can synchronously move with the galvanometer scanning device to the same station.

Abstract: A partitioned lifting forming type selective laser melting workbench, comprises at least forming platform (1) for powder-spreading and sintering and forming of workpiece, the forming platform (1) comprises forming inner abutment (1-1) and at least one forming outer abutment (1-2) which is sleeved on the forming inner abutment (1-1) and arranged in sequence from the inside to the outside in a radial direction, the forming inner abutment (1-1) and each forming outer abutment (1-2) are arranged in a manner of rise and fall, the forming inner abutment (1-1) or the forming outer abutment (1-2) falls independently, or the forming outer abutment (1-2) and the adjacent forming outer abutment or/and the forming inner abutment (1-1) fall together, it can form an area (2) to be subjected to powder-spreading for laser sintering and forming of workpiece.