Abstract: The present invention provides engineered polypeptides that are useful for the asymmetric synthesis of ?-hydroxy-?-amino acids under industrial-relevant conditions. The present disclosure also provides polynucleotides encoding engineered polypeptides, host cells capable of expressing engineered polypeptides, and methods of producing ?-hydroxy-?-amino acids using engineered polypeptides. Compared to other processes of preparation, the use of the engineered polypeptides of the present invention for the preparation of ?-hydroxy-?-amino acids results in high purity of the desired stereoisomers, mild reaction conditions, low pollution and low energy consumption. So, it has good industrial application prospects.

Abstract: The present invention provides engineered polypeptides that are useful for the asymmetric synthesis of ?-hydroxy-?-amino acids under industrial-relevant conditions. The present disclosure also provides polynucleotides encoding engineered polypeptides, host cells capable of expressing engineered polypeptides, and methods of producing ?-hydroxy-?-amino acids using engineered polypeptides. Compared to other processes of preparation, the use of the engineered polypeptides of the present invention for the preparation of ?-hydroxy-?-amino acids results in high purity of the desired stereoisomers, mild reaction conditions, low pollution and low energy consumption. So, it has good industrial application prospects.

Abstract: A method and apparatus for identifying an open phase of a circuit breaker on the basis of voltage. The method comprises: a protection apparatus measures three-phase voltages at two sides of a circuit breaker; respectively calculates a vector difference and an effective value of the voltages at two sides of the circuit breaker; when the phase voltages at two sides are both greater than 80% to 90% of a rated voltage, and the voltage vector difference at two sides of the one-phase or two-phase circuit breaker is greater than a set voltage, it is determined that the circuit breaker has an open phase; and actuates an alarming or tripping operation after a short time delay t.

Abstract: A relay protection method against LC parallel circuit detuning faults comprises the steps of: a relay protection device samples a current of a parallel LC, that is, a reactor and a capacitor, and samples a total current flowing through the whole LC; convert the current of the reactor into a current of an equivalent capacitor; calculate amplitudes of the current of the equivalent capacitor and a current of a realistic capacitor and calculate an amplitude of the total current flowing through the LC; calculate a current amplitude ratio of the equivalent capacitor to the realistic capacitor; and when the amplitude of the total current flowing through the LC is large enough, send an alarm signal or a trip after a setting time delay if the current ratio exceeds a preset upper and lower limit range. Also provided is a corresponding relay protection device.

Abstract: A method and apparatus for identifying an open phase of a circuit breaker on the basis of voltage. The method comprises: a protection apparatus measures three-phase voltages at two sides of a circuit breaker; respectively calculates a vector difference and an effective value of the voltages at two sides of the circuit breaker; when the phase voltages at two sides are both greater than 80% to 90% of a rated voltage, and the voltage vector difference at two sides of the one-phase or two-phase circuit breaker is greater than a set voltage, it is determined that the circuit breaker has an open phase; and actuates an alarming or tripping operation after a short time delay t.

Abstract: A relay protection method against LC parallel circuit detuning faults comprises the steps of: a relay protection device samples a current of a parallel LC, that is, a reactor and a capacitor, and samples a total current flowing through the whole LC; convert the current of the reactor into a current of an equivalent capacitor; calculate amplitudes of the current of the equivalent capacitor and a current of a realistic capacitor and calculate an amplitude of the total current flowing through the LC; calculate a current amplitude ratio of the equivalent capacitor to the realistic capacitor; and when the amplitude of the total current flowing through the LC is large enough, send an alarm signal or a trip after a setting time delay if the current ratio exceeds a preset upper and lower limit range. Also provided is a corresponding relay protection device.