Abstract: A line current iM(k0) of an M side of a first direct-current transmission line is collected at a moment k0. A line current iM(k0?ts) thereof is collected at k0?ts. At a moment k0, a differential value diM(k0) of a current of the side of the first direct-current transmission line is calculated according to the line current iM(k0) and the line current iM(k0?ts). It is determined whether the differential value diM(k0) of the current meets a protection enabling criteria. If so, direct-current protection for the M side of the first direct-current transmission line is enabled. A line current iM(j) of the M side of the first direct-current transmission line is collected at a moment j. A line current iM(j?ts) thereof is collected at a moment j?ts. A differential value diM(j) of the current of the M side of the first direct-current transmission line at the moment j is calculated according to the line current iM(j) and the line current iM(j?ts).

Abstract: A method and device for timing in time-varying distance protection based on multiple lines of a tower. The method includes: collecting an instantaneous current value at a time-varying distance protection installation location in the multiple lines of the tower, and acquiring preset parameters; calculating, according to the preset parameters and a multi-line ranging model, a multi-line ranging result; calculating, according to the preset parameters, the multi-line ranging result, and an adaptive calculation model, time of a section-II distance protection action and final time of a section-III distance protection action; and determining, according to the instantaneous current value, the preset parameters, and a cross-line failure auxiliary criterion model, final time of the section-II distance protection action.

Abstract: A method and device for starting direct-current (DC) transmission line protection, and a storage medium. The method includes: determining whether a sudden change of a DC line current at a present moment is greater than a sum of a memory start threshold and a maximum value in sudden changes of the DC line current within a time period preceding the present moment that is multiplied by a preset proportional coefficient, the time period being a time period between a moment preceding the present moment by a first duration and a moment preceding the present moment by a second duration; and starting DC transmission line protection in response to determining that the sudden change of the DC line current at the present moment is greater than the sum.

Abstract: A line double-end steady-state quantity distance measuring method and system based on an amplitude-comparison principle. According to the method and system, voltage values and current values of both sides of a line before and after a fault are collected (102), a voltage variable quantity and a current variable quantity of both sides of the line are calculated (103), and after a voltage phasor value and a current phasor value are determined according to the voltage variable quantity and the current variable quantity (104), the position of a short-circuit point is determined by performing iterative calculation on the voltage of the short-circuit point. The method is simple in principle, and can accurately recognize a fault point, achieving precise distance measurement of lines.

Abstract: Disclosed are a direct-current transmission line protection method and system based on pure current characteristics.

Abstract: A method and device for timing in time-varying distance protection based on multiple lines of a tower. The method includes: collecting an instantaneous current value at a time-varying distance protection installation location in the multiple lines of the tower, and acquiring preset parameters; calculating, according to the preset parameters and a multi-line ranging model, a multi-line ranging result; calculating, according to the preset parameters, the multi-line ranging result, and an adaptive calculation model, time of a section-II distance protection action and final time of a section-III distance protection action; and determining, according to the instantaneous current value, the preset parameters, and a cross-line failure auxiliary criterion model, final time of the section-II distance protection action.

Abstract: A method and device for starting direct-current (DC) transmission line protection, and a storage medium. The method includes: determining whether a sudden change of a DC line current at a present moment is greater than a sum of a memory start threshold and a maximum value in sudden changes of the DC line current within a time period preceding the present moment that is multiplied by a preset proportional coefficient, the time period being a time period between a moment preceding the present moment by a first duration and a moment preceding the present moment by a second duration; and starting DC transmission line protection in response to determining that the sudden change of the DC line current at the present moment is greater than the sum.

Abstract: Disclosed are a SARS-COV-2 antigen polypeptide, a recombinant adeno-associated virus (rAAV) expressing the polypeptide, and a vaccine containing the virus. A sequence of the antigen polypeptide is shown in SEQ NO. 1. and SEQ ID NO. 2. A method for preparing the recombinant adeno-associated virus comprises co-incubating pHelper, pRep2Cap5, and an expression vector, transfecting a cell in the presence of polyethyleneimine as a transfection reagent; culturing the cell, then collecting the cell by centrifugation, performing lysis and purification to obtain a purified liquid comprising the recombinant adeno-associated virus. The rAAV is delivered and expressed in vivo to produce a fusion antigen polypeptide, induces the production of serum neutralizing antibodies, which have a neutralizing titer to the novel SARS-COV-2 coronavirus and are expressed continuously; the rAAV composition can be used to immunize humans against the novel coronavirus pneumonia COVID-19.

Abstract: A current differential protection method for a self-adaptive half-wavelength line based on a time-difference method. Since an electrical distance of half-wavelength power transmission is long, after a fault occurs, there is an obvious time difference between the actuation times for protecting starting elements at two sides of a line. According to the principles of wave propagation, the position of a fault point can be determined by means of a difference between the actuation times for protecting the starting elements at the two sides of the line. By means of taking the fault point as a differential point, a current value at the differential point can be obtained according to a long line equation by means of the voltage and current at protection-mounted positions at the two sides of the line, and a differential current is then calculated.

Abstract: A method of free wave energy protection for a half-wavelength line based on a one-sided current includes: performing sampling and calculation on a current at protection measuring points to obtain variations in current sampling values; and activating a protective element to determine an occurrence time of a fault in a half-wavelength line. A free wave energy protection section includes a quick-action section, a basic section and a sensitive section, wherein the quick-action section, the basic section and the sensitive section serve as action criteria for performing protection with respect to the free wave energy of the half-wavelength line.

Abstract: A concomitant impedance protection method for a half-wavelength power transmission line includes that: three-phase currents and three-phase voltages of a relay protection device mounting position at an M side and a relay protection device mounting position at an N side of the half-wavelength power transmission line are acquired respectively; it is judged whether starting amounts of an M side and an N side meet starting conditions or not; a failure point F is determined according to a time difference when the starting amounts of the M side and the N side meet the starting conditions; and a relay protection action of the half-wavelength power transmission line is started according to concomitant impedance of the half-wavelength power transmission line.

Abstract: A method of free wave energy protection for a half-wavelength line based on a one-sided current includes: performing sampling and calculation on a current at protection measuring points to obtain variations in current sampling values; and activating a protective element to determine an occurrence time of a fault in a half-wavelength line. A free wave energy protection section includes a quick-action section, a basic section and a sensitive section, wherein the quick-action section, the basic section and the sensitive section serve as action criteria for performing protection with respect to the free wave energy of the half-wavelength line.

Abstract: A current differential protection method for a self-adaptive half-wavelength line based on a time-difference method. Since an electrical distance of half-wavelength power transmission is long, after a fault occurs, there is an obvious time difference between the actuation times for protecting starting elements at two sides of a line. According to the principles of wave propagation, the position of a fault point can be determined by means of a difference between the actuation times for protecting the starting elements at the two sides of the line. By means of taking the fault point as a differential point, a current value at the differential point can be obtained according to a long line equation by means of the voltage and current at protection-mounted positions at the two sides of the line, and a differential current is then calculated.

Abstract: A concomitant impedance protection method for a half-wavelength power transmission line includes that: three-phase currents and three-phase voltages of a relay protection device mounting position at an M side and a relay protection device mounting position at an N side of the half-wavelength power transmission line are acquired respectively; it is judged whether starting amounts of an M side and an N side meet starting conditions or not; a failure point F is determined according to a time difference when the starting amounts of the M side and the N side meet the starting conditions; and a relay protection action of the half-wavelength power transmission line is started according to concomitant impedance of the half-wavelength power transmission line.

Abstract: The invention provides a method for overcoming the influence of out-flowing current on bus differential protection. The method comprises the following steps: acquiring and processing branch current signals; selecting a fault bus, and determining the branch current with maximum amplitude from branches connected with the fault bus; calculating differential current and restraint current of a large differential element, and determining whether the large differential element acts. The method for overcoming the influence of out-flowing current on bus differential protection does not need to reduce the braking coefficient during splitting operation in a two-bus connecting mode, can adaptively improve the sensitivity of bus differential protection under an internal fault in the presence of out-flowing current, and simultaneously ensures the reliability under an external fault.

Abstract: The present invention discloses a self-locking mechanism for use in a drill chuck, comprising: clutch tooth sleeves, fixedly connected with the chuck body of the drill chuck and forming teeth; an oval deformation ring, having a substantially circular first shape and a substantially oval second shape, wherein the oval deformation ring has teeth on the side wall, with the teeth engaging with the teeth of the clutch tooth sleeve when the oval deformation ring is in the second shape; and a control sleeve, for controlling the conversion of the oval deformation sleeve between the first shape and the second shape. The present invention also discloses a force increasing self-locking drill chuck with said self-locking mechanism. The self-locking mechanism according to the present invention can be used in drill chucks of multiple structures, and provides a brand-new thought for the designs of the self-locking mechanisms of drill chucks.

Abstract: The present invention discloses a chuck mounted on a transmission shaft driven by a power source, and the chuck comprises a chuck body, plural jaws, a rear cap, an outer sleeve rotatablely fitted around the chuck body and located in front of the rear cap, and a transmission nut, characterized in that the chuck further comprises a drive pendulum support sleeve which is located between the outer sleeve and the transmission nut, connected with the outer sleeve and fitted around the chuck body; and a drive pendulum which is mounted on the drive pendulum support sleeve, swings between a first and second positions about its pivot axis, and has first and second drive portions, wherein the drive pendulum drives the transmission nut along a first transmission path through the first drive portion when it is in the first position, and drives the transmission nut along a second transmission path of more gripping force than the first transmission path through the second drive portion when it is in the second position.

Abstract: The present invention discloses a self-locking mechanism for use in a drill chuck, comprising: clutch tooth sleeves, fixedly connected with the chuck body of the drill chuck and forming teeth; an oval deformation ring, having a substantially circular first shape and a substantially oval second shape, wherein the oval deformation ring has teeth on the side wall, with the teeth engaging with the teeth of the clutch tooth sleeve when the oval deformation ring is in the second shape; and a control sleeve, for controlling the conversion of the oval deformation sleeve between the first shape and the second shape. The present invention also discloses a force increasing self-locking drill chuck with said self-locking mechanism. The self-locking mechanism according to the present invention can be used in drill chucks of multiple structures, and provides a brand-new thought for the designs of the self-locking mechanisms of drill chucks.

Abstract: A clamping structure for a handled tool including: (1) a chuck body, provided with gear teeth, ratchet and guiding holes, (2) a plurality of grippers, mounted in the guiding holes of the chuck body and having partial thread on one end; (3) an inner gear ring, (4) a control outer sleeve, having a plurality of control keys and a plurality of driving keys thereon, (5) a driving member having inner taper thread and a plurality of pinions thereon, wherein the inner taper thread engages with the threads of the grippers, and wherein the pinions, mounted to the driving member through pin shafts, engage with both the inner gear ring and the gear teeth of the chuck body, (6) a plurality of resilient anti-loose members with pawl.

Abstract: The present invention discloses a chuck mounted on a transmission shaft driven by a power source, and the chuck comprises a chuck body, plural jaws, a rear cap, an outer sleeve rotatablely fitted around the chuck body and located in front of the rear cap, and a transmission nut, characterized in that the chuck further comprises a drive pendulum support sleeve which is located between the outer sleeve and the transmission nut, connected with the outer sleeve and fitted around the chuck body; and a drive pendulum which is mounted on the drive pendulum support sleeve, swings between a first and second positions about its pivot axis, and has first and second drive portions, wherein the drive pendulum drives the transmission nut along a first transmission path through the first drive portion when it is in the first position, and drives the transmission nut along a second transmission path of more gripping force than the first transmission path through the second drive portion when it is in the second position.