Abstract: A channel state information (CSI) feedback method and apparatus. A terminal device receives a channel state information reference signal (CSI-RS) from a network device, and performs channel sounding based on the CSI-RS. The terminal device feeds back CSI to the network device based on a first codebook, wherein the first codebook is determined based on one or more transmit-end space-domain and frequency-domain column vectors and one or more receive-end space-domain and time-domain column vectors that represent a channel Alternatively, the first codebook is determined based on the one or more transmit-end space-domain and frequency-domain column vectors and one or more time-domain column vectors that represent the channel.

Abstract: This application relates to the field of communication technologies, and provides an information transmission method and an apparatus. In this method, a radio access network device sends, to a terminal device, first indication information indicating first information and second information and second indication information indicating a first quantity of DFT vectors, the first information indicates a first quantity of to-be-selected ports, and the second information indicates a first compression factor. The radio access network device further sends a reference signal to the terminal device. The terminal device sends downlink channel state information to the radio access network device based on the first indication information, the second indication information, and the reference signal. The compression factor is a compression factor of a complex coefficient matrix. There is a correspondence between the compression factor and a quantity of transport layers.

Abstract: A balance for air resistance testing is provided. The air resistance testing comprises 2N dual-hole beam sensors and an upper plate; wherein, the 2N dual-hole beam sensors are arranged beneath the upper plate and fixed to the upper plate; each dual-hole beam sensor comprises a beam, an upper hole and a lower hole, the upper hole and the lower hole are arranged along the longitudinal direction of the beam, the upper hole is arranged at the upper part of the beam, and the lower hole is arranged at the lower part of the beam.

Abstract: This disclosure provides a balance for air resistance testing, compromising 2N dual-hole beam sensors and an upper plate; wherein, the 2N dual-hole beam sensors are arranged beneath the upper plate and fixed to the upper plate; each said dual-hole beam sensor comprises a beam, an upper hole and a lower hole, the upper hole and the lower hole are arranged along the longitudinal direction of the beam, the upper hole is arranged at the upper part of the beam, and the lower hole is arranged at the lower part of the beam.