Abstract: A power converter and a method. When the voltage at the grid connection point exceeds the preset voltage range and an amplitude of a voltage output by the power conversion circuit is not greater than a voltage threshold, embodiments can control the amplitude of the current output by the power conversion circuit to be not greater than a second current threshold, where the second current threshold is greater than the first current threshold, and a ratio of an active current to a reactive current output by the power conversion circuit is constant or changes; or, when the amplitude of the voltage output by the power conversion circuit is greater than the voltage threshold, embodiments can control the amplitude of the current output by the power conversion circuit to be equal to the second current threshold, where the ratio of the active current to the reactive current changes.

Abstract: An islanding detection method includes: an alternating current frequency of an inverter is monitored. The alternating current frequency fluctuates within a preset range when in a normal mode. When an instantaneous shifting value of the alternating current frequency exceeds the preset range, a frequency detected before instantaneous shifting is a first frequency. When a frequency in first frequency data within a first preset time period is greater than or less than only the first frequency, an alternating current frequency detected when the first preset time period ends is a second frequency. Output power of the inverter is continuously adjusted based on a change in the current alternating current frequency. When a frequency in second frequency data within a second preset time period is greater than or less than only the second frequency, it may be indicated in time that islanding occurs in the inverter, and an islanding status is reported.

Abstract: A train crash energy management (CEM) optimization method based on machine learning is provided. The method includes: establishing a finite element model that is for an eight-marshalling train crash and considers a train energy absorption subsystem and a wheel-rail rolling contact behavior; establishing a machine learning database for train crash energy absorption; constructing a machine learning prediction model for the train crash energy absorption; and performing multi-objective optimization on CEM of a train based on machine learning.

Abstract: The present disclosure relates to a method and a device for predicting ability of a temporary plugging agent to plug cracks and a storage medium, and includes the following steps: calculating a plane elastic modulus of a core through experiments, acquiring a maximum force load of a specimen, calculating rock fracture toughness through the maximum force load, manufacturing an artificial crack model and placing it in a core holder, preparing temporary plugging deflection fluid by selecting a temporary plugging agent, injecting the temporary plugging deflection fluid into the artificial crack so as to calculate apparent fracture toughness of the temporarily plugged crack, and finally calculating a fracture pressure of the temporarily plugged crack based on the calculated rock fracture toughness and the plane elastic modulus of the core. Through the above method, the present disclosure provides a standard fracture pressure calculation method.

Abstract: A data access method includes obtaining a data access request for M storage devices, M being an integer greater than or equal to 2, determining a target access mode for the M storage devices based on the data access request, and performing data access on the storage devices based on access control signals matching the target access mode for the storage devices. The target access mode includes a first access mode and a second access mode. Access security and/or access speed generated when the data access is performed on the storage devices in the first access mode is different from access security and/or access speed generated in the second access mode.

Abstract: A multi-chip interconnection system includes a plurality of chips. A chip of the plurality of chips includes an extend serial peripheral interface (XSPI) master terminal, a data transmission terminal, an XSPI slave terminal, and a data reception terminal. The XSPI master terminal includes an advanced extensible interface (AXI) slave interface. The data transmission terminal accesses the AXI slave interface via an AXI bus. The XSPI slave terminal includes an AXI master interface. The data reception terminal accesses the AXI master interface via the AXI bus. An XSPI master terminal of a chip is connected to an XSPI slave terminal of another chip via an XSPI bus. The XSPI master terminal of the chip performs encoding on AXI information of the data transmission terminal of the chip received via the AXI bus and transmits encoded AXI information to the XSPI slave terminal of the another chip via the XSPI bus.

Abstract: A nano-emulsion composition having a small particle size and ultra-low concentration and a preparation method thereof is disclosed. The raw materials of the composition comprise, in terms of percentage by weight, 0.002% to 0.2% of a polymer-containing homogeneous microemulsion, water, and 99.998% to 99.8% of an organic salt solution or inorganic salt solution. The composition is prepared by diluting a polymer-containing homogeneous microemulsion with water or a salt solution. The polymer-containing homogeneous microemulsion is formed by mixing the following raw materials, in terms of percentage by weight: 8% to 40% of a surfactant, 0.5% to 10% of a polymer, 10% to 30% of an alcohol, 3% to 30% of an oil, 0% to 20% of a salt, and balance of water. The composition of the invention is low in concentration, low in cost, narrow in particle size distribution, good in stability, simple in preparation, and convenient for storage and use.

Abstract: A nano-emulsion composition having a small particle size and ultra-low concentration and a preparation method thereof is disclosed. The raw materials of the composition comprise, in terms of percentage by weight, 0.002% to 0.2% of a polymer-containing homogeneous microemulsion, water, and 99.998% to 99.8% of an organic salt solution or inorganic salt solution. The composition is prepared by diluting a polymer-containing homogeneous microemulsion with water or a salt solution. The polymer-containing homogeneous microemulsion is formed by mixing the following raw materials, in terms of percentage by weight: 8% to 40% of a surfactant, 0.5% to 10% of a polymer, 10% to 30% of an alcohol, 3% to 30% of an oil, 0% to 20% of a salt, and balance of water. The composition of the invention is low in concentration, low in cost, narrow in particle size distribution, good in stability, simple in preparation, and convenient for storage and use.