Abstract: Disclosed are a method and system for evaluating sonar self-noise at a ship design stage. The method includes: building a ship structure full-scale geometric simulation model; acquiring loss factors and sonar transducer space outfitting acoustic absorption coefficient material parameters; acquiring mechanical excitation, hydrodynamic excitation, and propeller excitation; inputting the loss factors and the sonar transducer space outfitting acoustic absorption coefficient material parameters into an established statistical energy evaluation model, and applying a mechanical excitation to a face plate of foundation of the built ship structure full-scale geometric simulation model, applying a hydrodynamic excitation to the surface of a ship hull, and applying a propeller excitation to a stern shaft to perform calculation of sonar self-noise of a ship to obtain total spectral density level of the sonar self-noise; and evaluating spectral density level calculation results by index requirements.

Abstract: Disclosed are a method and system for evaluating sonar self-noise at a ship design stage. The method includes: building a ship structure full-scale geometric simulation model; acquiring loss factors and sonar transducer space outfitting acoustic absorption coefficient material parameters; acquiring mechanical excitation, hydrodynamic excitation, and propeller excitation; inputting the loss factors and the sonar transducer space outfitting acoustic absorption coefficient material parameters into an established statistical energy evaluation model, and applying a mechanical excitation to a face plate of foundation of the built ship structure full-scale geometric simulation model, applying a hydrodynamic excitation to the surface of a ship hull, and applying a propeller excitation to a stern shaft to perform calculation of sonar self-noise of a ship to obtain total spectral density level of the sonar self-noise; and evaluating spectral density level calculation results by index requirements.

Abstract: A method for knitting fall-plate structures on warp-knitting machines, including: the fall-plate guide bar makes an overlap when the groove needle bar is going upward and the previous loop is held by the sinker bar; the groove needle bar and the tongue bar simultaneously go downward but these two items are kept not closed, and the overlapped yarn and the previous loop are slipping inside together; the groove needle bar go upward again while both the fall-plate yarn and the previous loop are held by the sinker bar, making the two yarns slip out of the groove needle. Meanwhile, a ground guide bar makes an overlap, finishing lapping. When moving the groove needle bar downward for a second time, retreating the old loop and the pressed yarn; forming a new loop, by the ground yarn; placing the pressed yarn under the new loop; and forming the fall-plate structures.

Abstract: A method for forming yarn pressing weave by using a groove pin warp knitting machine based on servo driving. The method is performed on a Raschel groove pin warp knitting machine, and specifically comprises: a. enabling a groove pin body (3) to rise for a first time, utilizing a sinker (5) to press against an old coil, utilizing a yarn pressing guide comb (1) to perform traverse movement before the pin, and finishing yarn laying; b. enabling the groove pin body (3) and a groove pin core (4) to descend, enabling the groove pin body (3) to be kept open, and enabling pressed yarn (6) and the old coil not to undergo ring sleeving and to together move into a pin hook; c.