Abstract: A device and a method for nondestructively detecting a transient characteristic of a conductive screw of a turbo-generator rotor are provided. The device includes a personal computer (PC), an extremely-steep pulse generator, an ultra-high-frequency double-isolation transformer, and a pulse emitting and coupling module, which are connected in sequence. The pulse emitting and coupling module is connected to a load. A synchronous pulse receiving non-inductive divider circuit synchronously receives a characteristic waveform from the load, and the synchronous pulse receiving non-inductive divider circuit is connected to an ultra-high-speed analog/digital (A/D) module through a nonlinear saturation amplifying circuit that amplifies a signal. The PC receives a signal from the ultra-high-speed A/D module. The load includes a positive or negative excitation lead loop that is in a 180° symmetrical and instantaneous short-circuit state and a rotor shaft.

Abstract: The present disclosure relates to a magnetic circuit of a loudspeaker and a loudspeaker, which can improve the non-linearity of magnetic permeability, thereby reducing the distortion of the loudspeaker. A magnetic circuit comprises a T-yoke with a base and a columnar portion protruding upward from the base, a magnetic steel arranged on the base, and a front sheet arranged on the magnetic steel, wherein the magnetic steel and the front sheet are arranged around a periphery of the columnar portion, and a short-circuit ring is arranged on an inner side of the magnetic steel and/or the front sheet. A first short-circuit ring is provided between the inner wall of the magnetic steel and the outer wall of the columnar portion, and a second short-circuit ring is provided on the inner wall of the front sheet.

Abstract: A device for detecting a slot wedge, an air gap and a broken rotor bar is provided, where a sequential circuit generates double concurrent pulses; the sequential circuit is connected to driving power modules; the driving power modules are connected to front-end interface circuits; the front-end interface circuits convert the double concurrent pulses into corresponding magnetic-field pulses; the magnetic-field pulses are transmitted to power supply terminals on adjacent phases of stator windings through impedance matching pins and coupled at a corresponding coil, air gap and squirrel cage rotor to generate single groups of cyclic rotating magnetic potentials; single rotating magnetic potentials are sequentially generated in adjacent slots on each of the phases of the stator windings; rotating electric potentials in magnetic circuits with two symmetrical phases are magnetically coupled to form distributed coupling magnetic field reflected full-cycle waves for reflecting a difference of a corresponding slot wedg

Abstract: The present invention discloses a method and a system for protecting root CA certificates in a virtualization environment. The method installs a root CA certificate security manager on a host computer. The root CA certificate security manager stores the lists of root CA certificates and provides certificate validation service to virtual machines via a read-only interface. When a virtual machine needs the verification of a certificate, it sends a certificate validation service request to the root CA security manager. The root CA certificate security manager provides certificate validation services to the virtual machine in response to the request.

Abstract: The present invention discloses a method and a system for protecting root CA certificates in a virtualization environment. The method installs a root CA certificate security manager on a host computer. The root CA certificate security manager stores the lists of root CA certificates and provides certificate validation service to virtual machines via a read-only interface. When a virtual machine needs the verification of a certificate, it sends a certificate validation service request to the root CA security manager. The root CA certificate security manager provides certificate validation services to the virtual machine in response to the request.