34results about How to "Improve short-term stability" patented technology

A dental implant can comprise 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 comprise 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.

An electroscope system excites a certain area of a surface of a sample to emit electrons with a characteristic distribution of kinetic energies. The analyzed area of the sample is excited by an electron beam produced by a field emission source. A monochromator energy filter for the electron beam is down-stream of the field emission source. The field emission electron source is preferably a Schottky source, and a monochromator energy filter reduces energy dispersion of the electrons of the electron beam to less than 0.2 eV. Microareas of linear dimensions on the order of ten nanometers may be analyzed while observing them. Information on the chemical state of the detected elements present at the surface of the examined microarea of the sample is gathered.

The invention discloses a method and a device for optimizing short-term stability parameters of an atomic frequency standard, which belong to the field of the atomic frequency standards. The method comprises the steps that a plurality of working parameter points are set; each working parameter point includes a plurality of experiment points which correspond to different parameters to be optimized, each parameter to be optimized corresponds to the plurality of experiment points, and the quantities of the corresponding experiment points are the same, the experiment points corresponding to the same parameter to be optimized are evenly distributed in a value area including two end points of the parameter to be optimized, at most one same experiment point exists in every two working parameter points, and the frequency of each experiment point in all the working parameter points is the same; each parameter to be optimized includes modulation depth, modulation frequency and microwave power; according to each working parameter point, the modulation depth, the modulation frequency and the microwave power are respectively regulated; and frequency discrimination gradient of the atomic frequency standard corresponding to each working parameter point is calculated, and the optimal working parameter point is selected. The method and the device improve 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 method and device for taming a rubidium clock by combining common view and one-way time service of a Beidou satellite. The device comprises a host provided with a display screen. A main control board is installed in the host, and is provided with a Beidou and time signal measurement module, a data collection processing and display control module, a power module, and a phase locking and rubidium clock module. According to the method, the working principle is simple, the problem that a traditional Beidou cannot trace the UTC time during rubidium clock taming and the time service deviation is large is solved, and meanwhile the problems that the taming period of taming a rubidium clock through a Beidou common-view method is too long, common-view equipment breaks down or a communication link is abnormal, and time difference cannot be obtained for taming are solved.

A device for actively calibrating optical fiber transmission of microwave signals by means of a photoelectric oscillator comprises a central station and a base station, wherein the central station is connected with the base station through a single-mode optical fiber. The device can overcome defects of a traditional electronic method at aspects of bandwidth, weight, size, electromagnetic interference, etc. Furthermore the device overcomes a bottleneck of realizing stable-phase transmission of high-frequency microwave signals through electronic technology.

The invention discloses a perpendicular coupling nanometer optical waveguide dual-optical-path chip atomic clock which comprises a laser, light beams emitted by the laser enter a Y waveguide beam splitter through coupling of a perpendicular coupling optical grating I, one beam of light is output after passing by a phase modulation unit, another beam of light is output after regulation compensation, the two beams of light are output after passing by the perpendicular coupling optical grating I and a perpendicular coupling optical grating II respectively, enter a rubidium atom air chamber after passing by a polarizing film, an attenuation plate and a wave plate and after collimation and focussing and are input into an integrated circuit chip by a subtracter after emitted and converted into electrical signals by a detection unit, and the integrated circuit chip controls the laser and the phase modulation unit. According to the scheme, luminous power fluctuation and frequency fluctuation noise influences can be reduced greatly through dual-optical-path common-mode rejection, the signal-to-noise ratio of a CPT atomic clock is effectively improved, and accordingly, the short period stability of a chip level atomic clock can be improved greatly.

The invention discloses high-stability combined region time service frequency generation equipment and aims to provide time service frequency generation equipment with high reliability, high length stability and a wide application range. The invention adopts the technical scheme that a receiving switching unit inputs two paths of selected satellite second signals from different sources into a locking unit to carry out frequency locking, two paths of phase-locked standard frequency signals generated by the locking unit and are respectively output to a signal processing unit A and a signal processing unit B; one path of satellite second signal is also used for carrying out frequency correction on a rubidium clock connected in parallel between a three-selection two-open device and a first analog phase-locked loop PLL_A, and one path of standard frequency signal is generated and transmitted to a signal processing unit C; and the signal processing units carry out signal shaping, amplification, shunting and coding on three paths of standard frequency signals from different sources, the obtained signals are subjected to frequency division, output to a far-end time service unit and are converted into optical signals by an optical-electrical converter, and the optical signals are transmitted to an equipment machine room by one or multiple paths of optical fibers and then are converted into electric signals, and the electric signals are transmitted by an antenna so as to complete a clock time service of a receiving end.

The invention discloses an end-coupling nano optical waveguide type dual-optical-path chip-scale atomic clock comprising a laser device. An emergent light beam of the laser device enters a Y-waveguide beam splitter through coupling of the end-coupling input end, wherein one light beam is outputted after passing through a phase modulation unit while the other light beam is outputted after adjust compensation, and the two light beams are outputted after passing through a vertical coupling grating II and a vertical coupling grating III respectively and sequentially pass through a polaroid, attenuation slices, a wave plate, collimation and focusing prior to entering an air chamber. After being emergent, the two light beams are converted into electrical signals through a detection unit, the electrical signals are inputted into an integrated circuit chip through a subtracter, and the integrated circuit chip is used for regulating and controlling the laser device and the phase modulation unit. The end-coupling nano optical waveguide type dual-optical-path chip-scale atomic clock has the advantages that the effect of optical power fluctuation and frequency fluctuation noise can be greatly weakened and the signal-to-noise ratio of the CPT atomic clock can be effectively improved through dual-optical-path common-mode rejection, so that short-term stability of the chip-scale atomic clock can be greatly enhanced.

The invention provides a time keeping method for controlling a voltage-controlled crystal oscillator based on a temperature change difference, and the method comprises the steps: collecting the ambient temperature around the crystal oscillator when the crystal oscillator normally operates to track a reference source, and averaging the ambient temperature through accumulation to generate a temperature reference; subtracting the reference temperature from the ambient temperature around the crystal oscillator after the reference source is disconnected, and calculating the temperature deviation around the crystal oscillator; and converting the temperature deviation into the voltage-controlled voltage of the crystal oscillator, and eliminating the frequency deviation of the crystal oscillator at the holding moment. According to the invention, the crystal oscillator is controlled according to the relationship between the temperature deviation and the control quantity of the voltage-controlled crystal oscillator, so that the short-term stability of the crystal oscillator is not obviously reduced, and the retention capability of the output time signal of the crystal oscillator is improved.

Methods and devices for calibrating a radiotherapy system are disclosed. The method includes providing a detection medium that responds to exposure to ionizing radiation, and preparing a calibration dose response pattern by exposing predefined regions of the detection medium to different ionizing radiation dose levels. The method also includes measuring responses of the detection medium in the predefined regions to generate a calibration that relates subsequent responses to ionizing radiation dose. Different dose levels are obtained by differentially-shielding portions of the detection medium from the ionizing radiation using, for example, a multi-leaf collimator, a secondary collimator, or an attenuation block. Different dose levels can also be obtained by moving the detection medium between exposures. The disclosed device includes a software routine fixed on a computer-readable medium that is configured to generate a calibration that relates a response of a detection medium to ionizing radiation dose.

Thisa invention relates to a method for integrating modulator in a feedback laser module characterizing in applying a secondary cooling technology and a photoelectric separation technology to increase the short and long term stability of output optical power, then applyihng a refrigerator to control the temperature and monitor its temperature with a thermistor to adjust and stabilize laser diode source in the applification of WDM, finally introducing passive optical applicances and laser module with the wavelength monitor and control ability to integrate and package a micro-optical demodulator module in a 14-feet butterfly high power feed back laser.

The invention relates to a distributed online monitoring system for underwater sound production of marine mammals, which belongs to the field of sound signal acquisition and processing and comprises acoustic monitoring nodes and ashore terminals which are distributed. The acoustic monitoring node is composed of a hydrophone, an acoustic signal acquisition module, a real-time processing and identification module, a synchronous positioning module and a real-time communication module; the acoustic monitoring nodes are distributed in water and convert acoustic signals into data signals; the real-time processing recognition module recognizes which kind of animal sends out the sound signal in real time, and records the time when the signal is detected; the synchronous positioning module is used for resolving the position of the acoustic monitoring node and realizing clock synchronization of the synchronous positioning module, and the real-time communication module is used for sending working information to a shore terminal; the ashore terminal receives the information of each acoustic monitoring node and realizes the positioning of a sounding mammal; and the system provided by the invention can realize real-time on-line monitoring of underwater sound production of animals in an on-line and long-distance manner.