37results about How to "Improve short-term stability" patented technology

A dental implant can include a shaft defining a longitudinal axis and having an apical end, a coronal end, and an exterior surface. A portion of the exterior surface can include a porous material. The dental implant can include at least one thread, including a non-porous material, having an interior surface and a bone-engaging surface. The interior surface can engage and wind around the exterior surface of the shaft and the bone-engaging surface can extend outwardly from the exterior surface of the shaft. The shaft can include one or more channels configured to communicate a flowable material, stored within the shaft, to the exterior surface. Each channel can include an opening at the exterior surface to release the flowable material. At least one channel can extend between a cavity of the shaft and the exterior surface and can optionally be angled toward the apical end.

The invention discloses a method and device for optimizing short-term stability parameters of an atomic frequency standard, belonging to the field of atomic frequency standards. Method: set multiple working parameter points; each working parameter point includes multiple experimental points and each experimental point corresponds to a different parameter to be optimized, and each parameter to be optimized corresponds to multiple experimental points and the number of corresponding experimental points is the same. The experimental points corresponding to the same parameter to be optimized are evenly distributed in the value range of the parameter to be optimized and include the two ends of the value range. There is at most one experimental point in every two working parameter points that is the same, and each experimental point is in all The number of occurrences in the working parameter points is equal; the parameters to be optimized include modulation depth, modulation frequency and microwave power; adjust the modulation depth, modulation frequency and microwave power according to each working parameter point; calculate the frequency discrimination of the atomic frequency standard corresponding to each working parameter point Slope, select the best working parameter point. The invention improves the short-term stability of the atomic frequency standard.

The invention discloses a moon observation system which is composed of an astronomical telescope, a ground-based microwave radiometer, a two-dimensional scanning mechanism and a controller. The systemis simple in structure and easy to implement. The ground-based microwave radiometer is installed on a two-dimensional turntable, the pitch angle of the initial position of the moon is obtained by theastronomical telescope, the initial position is calibrated by the controller, and the two-dimensional turntable is controlled to automatically track and scan the track of the moon; the moon brightness temperature signal is reflected by the antenna to enter an antenna feed system and enters a radiation receiver after polarization separation, and a voltage acquisition signal and a variance curve can be obtained in real time after detection and the moon brightness temperature value can also be calculated and thus the test efficiency can be effectively improved. The moon observation system has certain universality and can be applied to moon brightness temperature measurement based on ground-based microwave radiometers of different frequency bands to explore the stability and time distributioncharacteristics of microwave radiation characteristics.

The invention discloses a coherent population trapping an atomic frequency standard and a method for improving its short-term stability, belonging to the field of atomic frequency standards. The atomic frequency standard includes: a voltage-controlled crystal oscillator; a linear polarization excitation unit, which is used to generate a microwave search signal according to the output frequency of the voltage-controlled crystal oscillator; a physical unit, which is used to generate an optical detection signal under the action of the microwave search signal; a servo loop, It is used to perform synchronous phase detection on the optical detection signal to generate a synchronous phase detection signal; the control unit is used to generate a correction voltage based on the synchronous phase detection signal to act on the voltage-controlled crystal oscillator; the system relaxation time detection unit is used to detect the atomic frequency standard system Relaxation time Δt; the control unit is also used for timing control of the optical switch and servo loop in the physical unit according to the system relaxation time Δt, after controlling the optical switch in the physical unit to be turned on for N Δt time lengths, control The servo loop performs synchronous phase detection on the optical detection signal generated by the physical unit.

A device for actively calibrating the phase of a microwave signal transmitted by an optical fiber using a photoelectric oscillator includes: a central station and a base station, and the central station and the base station are connected through a single-mode optical fiber. The invention can overcome the disadvantages of traditional electronic methods in terms of bandwidth, weight, volume, electromagnetic interference, etc., and break through the bottleneck of electronic technology to realize stable phase transmission of high-frequency microwave signals.