39 results about "Cosmic ray" patented technology

The invention discloses an aviation radiation dose global distribution real-time calculation system based on ground detection equipment, which belongs to the technical field of radiation detection and comprises a ground radiation detection module, a dose simulation module and a data correction module. The ground radiation detection module is used for continuously collecting ionizing radiation data of an atmospheric bottom layer in a calm state and a solar high-energy particle event so as to improve data precision and a signal-to-noise ratio under a weak dose, and the dose simulation module receives latitude and longitude, height and time parameters of an aviation flight path, and calculates a standard atmospheric model and a cosmic ray energy spectrum in combination with the standard atmospheric model and the cosmic ray energy spectrum. The data processing module is used for calculating theoretical dose rates and particle type distribution of different height levels based on a Monte Carlo method and outputting the theoretical dose rates and the particle type distribution, and the data correction module is used for dynamically correcting parameters and weights of simulation results by combining measured data based on a deep learning algorithm of deep learning, so that adaptive fusion of the simulation data and the measured data is realized; and the ground radiation detection module comprises a semiconductor radiation detector, a data acquisition and preprocessing unit, a remote control module and a network communication module. The system has the characteristics of high real-time performance and wide coverage range.

The present disclosure describes a method for conditioning and preprocessing raw cosmic ray data to extract features and generate a binary string representing the inherent randomness in the data. Measurable characteristics of cosmic ray particles, such as arrival times and amplitudes, are processed to create random binary sequences. These binary strings are then used to train a generative adversarial network (GAN) framework. In the GAN framework, the generator creates random sequences resembling the target distribution, which matches the entropy of the conditioned cosmic data. The discriminator evaluates the generated sequences by comparing them to the conditioned cosmic data and assigns a randomness score that characterizes the quality of the generated sequences. This adversarial process ensures the generation of high-quality random sequences that are statistically indistinguishable from the conditioned input data.

The invention discloses a silver river cosmic ray radiation protection method based on a proton heavy ion Bragg peak. The method comprises the following steps: determining minimum energy information of ions allowed to enter a to-be-protected region; according to the ion charge, mass, energy and minimum energy information, the magnetic field intensity minimum value used for deflecting low-energy part ions with energy lower than the minimum energy information before the ions enter the to-be-protected area is given; giving the magnetic field intensity for deflecting the ions according to the minimum value of the deflection magnetic field intensity of the different types of ions; according to the magnetic field intensity, magnetic field power supply intensity is set, silver river cosmic ray protection is carried out on the to-be-protected area, and Bragg peaks of an ion dose distribution curve are prevented from being deposited in the to-be-protected area. The deposition dosage of the to-be-protected area is reduced, and effective protection of silver river cosmic rays is achieved.

The present invention proposes a method and system for selecting a solar cosmic ray model, including a selection requirement instruction for a solar cosmic ray model. Based on the purpose of analysis, research or experiment, the data requirements of the corresponding solar cosmic ray model are obtained from the selection requirement instruction. Since the single particle effect brought by solar cosmic rays is mainly related to the energy and flux of transient particles, while the total ionization dose effect and the total displacement dose effect are closely related to the energy and cumulative flux (infusion) of cumulative particles, of course, astronauts will also be threatened by the instantaneous flux and the cumulative flux. Therefore, it is necessary to select a solar cosmic ray model that meets the requirements of the solar cosmic ray model selection instruction from a variety of different angles in this application according to the on-orbit period of the spacecraft, the type of effect concerned, whether the object of analysis is effect or probability, etc.

The present disclosure describes a method for conditioning and preprocessing raw cosmic ray data to extract features and generate a binary string representing the inherent randomness in the data. Measurable characteristics of cosmic ray particles, such as arrival times and amplitudes, are processed to create random binary sequences. These binary strings are then used to train a generative adversarial network (GAN) framework. In the GAN framework, the generator creates random sequences resembling the target distribution, which matches the entropy of the conditioned cosmic data. The discriminator evaluates the generated sequences by comparing them to the conditioned cosmic data and assigns a randomness score that characterizes the quality of the generated sequences. This adversarial process ensures the generation of high-quality random sequences that are statistically indistinguishable from the conditioned input data.

The invention belongs to the technical field of laser Raman gas analysis and detection, and particularly relates to a zero drift suppression and ray interference resistance method for laser Raman gas detection. According to the method, the interference of noise and cosmic rays in the laser Raman gas quantitative detection process can be reduced, so that the precision of a laser Raman gas quantitative detection result is relatively high, a data abnormal phenomenon hardly exists, and the probability of zero drift can be reduced. According to the method, the influence caused by noise and cosmic rays can be eliminated in a large probability.

The application discloses a cosmic ray cluster muon navigation positioning point feature extraction method, and relates to the technical field of navigation guidance and control. The steps are as follows: S1, through the upper and lower two particle detectors in the closed navigation area, accumulate and collect muon data penetrating into the navigation area, and obtain muon data for effective imaging through time sequence denoising and spatial filtering; S2, a projection horizontal plane is constructed in the closed navigation area and is divided into a grid, the number of muons penetrating into each cell of the grid and the penetrating point position are determined, the muons affecting imaging in the possible abnormal muons in each cell are identified and deleted; S3, the muon distribution density in each cell on the projection horizontal plane is re-estimated, a color heat map of the navigation area is generated through normalization and color mapping; the method realizes intuitive, clear and efficient color heat map imaging of the navigation positioning hotspot area, reduces the processing difficulty of the muon navigation positioning map, and ensures the identification efficiency and reliability of the navigation positioning feature points.

The invention provides an automatic plant farm control system in a planetary environment. The automatic plant farm control system comprises a central control system, an environment monitoring system, a plant cultivation cabin, a nutrient management system, an automatic sowing and harvesting system and a resource recovery and circulation system. Under the conditions of extreme temperature difference, low air pressure and non-earth type atmosphere, temperature, humidity and gas balance environment needed by plants can be provided, and adaptive growth of the plants on different planets is ensured. And secondly, cosmic rays, solar wind and planetary surface radiation can be resisted. Besides, a closed-loop resource circulation system is developed especially for the current situation that deep space resources are deficient, multi-stage purification and recovery of water resources and efficient degradation and utilization of waste are achieved, and the resource use efficiency is remarkably improved. And finally, aiming at the deep space communication delay problem, the AI autonomous decision technology is adopted, environment regulation and control, irrigation management and fault repair can be completed without human intervention, and deep space task requirements are met.

The invention discloses a cosmic ray detection array triggering method based on density clustering, and the method comprises the steps: carrying out the threshold-crossing discrimination of the amplitudes of input signals of all channels of a cosmic ray detection array at an initial a moment, and obtaining channels with the signal amplitudes exceeding a set threshold value; generating a neighborhood of which the radius of the threshold channel is R, and obtaining a channel number corresponding to the neighborhood according to the channel arrangement layout of the cosmic ray detection array; counting the sum NL of the number of threshold-crossing channels which accumulatively appear in the neighborhood in a time window with the length of L, comparing the neighborhood density Mb with the set neighborhood minimum density Mmin, and judging whether a trigger signal is generated or not according to a comparison result; and obtaining the number of all channels in the neighborhood of the over-threshold channel corresponding to the triggering moment, and transmitting the number to a back-end system. According to the method, the problem that the triggering efficiency of a triggering algorithm based on multiple numbers or adjacent pixel positions on a physical case is low can be solved, and the triggering efficiency of a system on the physical case is effectively improved.

The utility model relates to a high-sensitivity radioactive gas activity measuring device which comprises a set of double-beta plastic scintillator detector, two sets of gamma detectors, an anti-cosmic ray detector group and a digital coincidence circuit. The double-beta plastic scintillator detector and the gamma detectors are arranged in the lead shielding chamber, the double-beta plastic scintillator detector is arranged between the two gamma detectors, and mutual interference among radioactive gases in the double-beta plastic scintillator detector can be eliminated through coincidence and anticoincidence among four paths of signals; and the anti-cosmic ray detector group is used for shielding coincidence signals generated by cosmic rays in the double-beta plastic scintillator detector and the gamma detector. According to the utility model, a gamma detector original spectrum, an anti-cosmic ray gamma spectrum, a beta-gamma coincidence spectrum and an anti-cosmic ray beta-gamma coincidence spectrum, wherein the beta-gamma coincidence spectrum and the anti-cosmic ray beta-gamma coincidence spectrum are used for eliminating mutual influence among different radioactive gases. According to the utility model, synchronous measurement of different radioactive gases can be realized, and the detection sensitivity of the radioactive gases can be greatly improved.

The utility model discloses a cosmic ray scientific demonstration instrument. The cosmic ray scientific demonstration instrument comprises an evaporation layer (1), a transparent shell demonstration layer (2) and a refrigeration layer (3) which are sequentially stacked from top to bottom, wherein two ends of the transparent shell demonstration layer (2) are respectively connected with the evaporation layer (1) and the refrigeration layer (3) in a sealed manner to form a transparent sealed space; the evaporation layer (1) is used for carrying out low-temperature heating on ethanol or methanol to generate steam and enabling the steam to enter the transparent shell demonstration layer (2); the refrigeration layer (3) is used for reducing the temperature of steam in the transparent shell demonstration layer (2) to form supersaturated steam; and the transparent shell demonstration layer (2) is used for observing the track of incident ray particles by using the stored supersaturated steam. The device is ingenious and compact in structural design, can clearly observe the motion trail of particles, has the characteristics of large observation space, obvious demonstration effect, good mobility and the like, is suitable for various demonstration scenes, and can demonstrate to multiple persons at the same time.

The present invention relates to the technical field of cable preparation, and specifically to a process for preparing a cosmic ray-resistant and high-temperature resistant cable, which includes an extrusion chamber with a conical structure formed in a first extrusion hood and a second extrusion hood, a circular extrusion port formed at the connection between the first extrusion hood and the second extrusion hood and a coating cylinder, and a cable passing through the extrusion port. One end of the extrusion chamber is connected to a buffer cylinder, and the other end is connected to the coating cylinder. The place where the extrusion chamber is connected to the coating cylinder forms a circular extrusion port. The connection between the first extrusion hood and the second extrusion hood and the coating cylinder is respectively provided with seals in a symmetrical layout. The seals are all conical structures, and the opposite end of the two seals is the narrower end of the conical structure. The narrower end of the seal extends a distance toward the front end to form a circular sealing portion.

The invention relates to a high-sensitivity radioactive gas activity measuring device and method. The device comprises a set of double-beta plastic scintillator detector, two sets of gamma detectors, an anti-cosmic ray detector group and a digital coincidence circuit. The double-beta plastic scintillator detector and the gamma detectors are arranged in the lead shielding chamber, the double-beta plastic scintillator detector is arranged between the two gamma detectors, and mutual interference among radioactive gases in the double-beta plastic scintillator detector can be eliminated through coincidence and anticoincidence among four paths of signals; and the anti-cosmic ray detector group is used for shielding coincidence signals generated by cosmic rays in the double-beta plastic scintillator detector and the gamma detector. According to the method, the original spectrum of the gamma detector, the anti-cosmic ray gamma spectrum, the beta-gamma coincidence spectrum without mutual influence among different radioactive gases and the anti-cosmic ray beta-gamma coincidence spectrum can be obtained. According to the invention, synchronous measurement of different radioactive gases can be realized, and the detection sensitivity of the radioactive gases can be greatly improved.

1. Name of the Design Product: Cosmic Ray Demonstrator. 2. Use of the Design Product: As a demonstrator for observing cosmic rays, used to observe the movement trajectories of ray particles when cosmic α-rays, β-rays, and γ-rays pass through the hollow space of the demonstrator. 3. Design Key Points of the Design Product: Lies in the shape. 4. Picture or Photograph that Best Illustrates the Design Key Points: Perspective View 1.

The present disclosure describes a method for conditioning and preprocessing raw cosmic ray data to extract features and generate a binary string representing the inherent randomness in the data. Measurable characteristics of cosmic ray particles, such as arrival times and amplitudes, are processed to create random binary sequences. These binary strings are then used to train a generative adversarial network (GAN) framework. In the GAN framework, the generator creates random sequences resembling the target distribution, which matches the entropy of the conditioned cosmic data. The discriminator evaluates the generated sequences by comparing them to the conditioned cosmic data and assigns a randomness score that characterizes the quality of the generated sequences. This adversarial process ensures the generation of high-quality random sequences that are statistically indistinguishable from the conditioned input data.

To uniformly induce nuclear reactions on the surface of a hydrogen-containing metal in room-temperature nuclear fusion.SOLUTION: In a case where the excitation time 1 / (F×A×V) is estimated when F is the flux density of high-energy excitation source particles such as cosmic rays, A is the capture coefficient of the hydrogen-containing metal for the excitation source particles, and V is the volume of crystal grains constituting the hydrogen-containing metal, the excitation time becomes more than one million years under present background neutron conditions on Earth for typical current grain sizes. Thus, only an extremely small portion of the entire material can undergo nuclear reactions, revealing the need for a fundamental solution. The most effective method is single crystallization or large-grain polycrystallization, which significantly improves the excitation time. Dramatic improvement is also achievable by artificially supplying high-energy particles to the hydrogen-containing metal using LC resonance type accelerators or the like.SELECTED DRAWING: Figure 9

The application discloses a muon incident position prediction method and system, and belongs to the technical field of muon detection. The application sets up a multi-layer muon detection array in a to-be-detected area, and establishes a reverse propagation correction track based on muon events obtained by each detection unit. After voxelization of the to-be-detected area, track response, energy response, scattering response and propagation uncertainty response are generated according to the distance between voxels and the reverse propagation correction track, and voxel fingerprint features are spliced. Variance is taken for the track, energy and scattering response at each time, and reverse mapping is performed to obtain stable evolution features. The fingerprint features and the stable evolution features are fused to construct a stability-gated correction-type enhanced adjacency matrix, and a graph convolution classification network is used for position prediction. The application significantly improves the prediction accuracy of the muon incident position through multi-dimensional response fusion and stability enhancement mechanism, and can be widely applied to muon transmission imaging and cosmic ray monitoring scenes.

1. The name of the design product: cosmic ray particle observation device. 2. The use of the design product: for cosmic ray particle observation. 3. The design points of the design product: in shape. 4. The picture or photo that best shows the design points: perspective view. 5. Other circumstances that need to be explained: the front view and part A of the perspective view show transparent material; the rear view and part B of the perspective view show transparent material; the left view and part C of the perspective view show transparent material; the right view and part D of the perspective view show transparent material; the top view and part E of the perspective view show transparent material.

The invention discloses a method for measuring the formation year of a solid object based on cosmic ray information, and relates to the technical field of year detection.The method comprises the following steps that a host is started for environment calibration, and after preheating self-inspection of the host is normal, a sample is correspondingly placed according to the size of the object or an information collection rod plate is used for making contact with the sample; a detection program is started, signal coupling is optimized, a resonance signal is captured after a microwave field is added to a host, a time is judged, and the number of years is solved and substituted into a model to calculate the year; after about 3 minutes of detection, a year accurate to a single bit is displayed, and reports containing articles, years and detection conditions can be stored or printed. According to the method, the initial paramagnetic center information formed by the cosmic rays in the solid object is directly read and analyzed, accurate calculation is carried out by combining the generation rate model calibrated by factors such as normal temperature and humidity, nondestructive and rapid detection without depending on chemical component analysis can be realized, and finally a formation age result accurate to the year is obtained.

This invention discloses a spectral analysis method, apparatus, device, and storage medium. It includes: acquiring raw spectral data to be analyzed; preprocessing the raw spectral data to obtain preprocessed spectral data; performing multi-peak fitting on the preprocessed spectral data using an iterative residual peak-finding fitting algorithm to obtain a final fitted spectrum and a final residual spectrum; and generating spectral analysis results based on the final fitted spectrum and the final residual spectrum. Preprocessing the raw spectral data effectively eliminates background interference, cosmic ray pseudo-signals, and random noise, improving the signal-to-noise ratio of the spectral data. Using the iterative residual peak-finding fitting algorithm for multi-peak fitting accurately identifies and fits all significant spectral peaks, avoiding underfitting and overfitting problems, and improving the accuracy of multi-peak fitting. The generated spectral analysis results can accurately extract core feature indicators, and the fitting quality can be verified through residual spectroscopy, ensuring that the analysis results are accurate and reliable, truly reflecting the structural characteristics of the material.

The invention relates to a method and a device for deducting cosmic rays in real time in environmental radiation monitoring. The method comprises the following steps: constructing a first linear equation of a background dose equivalent rate about an environmental dose equivalent rate and a cosmic ray dose equivalent rate; acquiring a plurality of radiation dose rates in the environment measured by the plurality of detectors at the current moment; constructing a plurality of second linear equations of radiation dose rates with respect to cosmic ray dose equivalent rates; determining a background dose equivalent rate based on simultaneous equation and equation set; simultaneous operation is carried out on the second linear equation set, and the cosmic ray dose equivalent rate is determined; and deducting the cosmic ray dose equivalent rate at the current moment based on the first linear equation and the background dose equivalent rate, and determining the environmental dose equivalent rate. According to the invention, the dose equivalent rate generated by the cosmic rays in real time is calculated, and the dose equivalent rate of the cosmic rays is deducted in real time, so that the technical effects of improving an original constant value into the dose equivalent rate of the cosmic rays generated in real time and reducing the deviation of the environmental dose rate equivalent are achieved.

The application discloses a small celestial body density detection device and method based on cosmic rays. The small celestial body density detection device comprises a time flyer, the time flyer comprises a first time flyer and a second time flyer arranged along a first direction, and a mounting cavity is arranged between the time flyer and the second time flyer; a lead absorbing body is arranged for absorbing part of background particles; a radiation body is arranged for absorbing muons and radiating Cherenkov photons; a detection layer comprises a first detection layer and a second detection layer, and the first detection layer and the second detection layer are respectively arranged at two opposite side ends of the radiation body along the first direction; the Cherenkov photons projected on the detection layer form a Cherenkov light ring, and the detection layer is used for converting optical signals into electrical signals; and a collection and processing module is arranged for collecting the number of electrical signals and inverting the attenuation flux of muons.

The application provides a MCP life test method and system for high-energy cosmic rays, and aims to solve the technical problem that the current method of evaluating MCP life by marking the output brightness gain change of an image intensifier is prone to system error. The test method comprises the following steps: sequentially placing an electron cathode, a to-be-tested MCP sample and an anode plate in a high-vacuum tube, sequentially arranging an adjustable diaphragm and the high-vacuum tube on a high-energy light source incident light path; closing the adjustable diaphragm, turning on the high-energy light source and calibrating the high-energy light source; sequentially applying a high-voltage electric field to the anode plate, the to-be-tested MCP sample and the electron cathode; adjusting the position and aperture size of the adjustable diaphragm; after electrons sequentially undergo electron multiplication and electron collection through the to-be-tested MCP sample and the anode plate, the anode plate outputs current; detecting the output current of the anode plate, taking the maximum laser intensity as a reference, and performing normalization processing on the laser intensity in the measurement interval; and obtaining the life of the to-be-tested MCP sample.

The application provides a Raman spectrum cosmic ray peak identification method based on multi-feature fusion, which can accurately identify typical high and narrow cosmic ray peaks and narrow but low, high but wide and overlapping variant peaks. The identification steps comprise: 1) performing first-order differential processing on the original Raman spectrum to obtain a differential spectrum, and then performing threshold screening on the positive and negative differential vertexes in the differential spectrum to obtain a candidate peak set; 2) taking the positive and negative differential vertexes of the candidate peak as starting points, performing percentile threshold detection on the differential spectrum to preliminarily locate the peak boundary, and then performing percentile threshold detection on the original Raman spectrum to accurately locate the left and right boundary points of the peak; 3) calculating the left edge pixel width, right edge pixel width, boundary point pixel width, half-peak height pixel width and differential vertex pixel width of the candidate peak, then performing weighted fusion calculation on the pixel width to obtain a score value, and finally identifying the cosmic ray peak according to the score threshold.

This application provides a cosmic ray identification method, electronic device, and storage medium. The method includes: acquiring a Raman spectrum set of a sample to be tested; determining the column-oriented robust Z-score of each wavenumber point in the Raman spectrum set under each wavenumber series, and determining a column threshold based on the Raman spectrum set and the column-oriented robust Z-score of each wavenumber point under each wavenumber series; determining the row-oriented locally robust Z-score of each wavenumber point in the Raman spectrum set under each spectral row, and determining a row threshold for each spectral row based on the row-oriented locally robust Z-score of each wavenumber point under each spectral row; identifying each cosmic ray point in the Raman spectrum set based on the column-oriented robust Z-score of each wavenumber point under each wavenumber series, the column threshold, the row-oriented locally robust Z-score of each wavenumber point under each spectral row, and the row threshold for each spectral row, and restoring the light intensity at each cosmic ray point to obtain the target Raman spectrum set of the sample to be tested, thereby improving the accuracy of cosmic ray identification.

A method for calibrating a photoelectric conversion module of a gamma detector is provided, where the gamma detector includes a scintillation crystal and a plurality of photomultiplier tubes. The method includes acquiring a plurality of sets of background data, each including photoelectric signals generated by the photomultiplier tubes based on an interaction of the scintillation crystal with a cosmic ray, determining interaction positions based on the background data, where the scintillation crystal interacts with cosmic rays respectively, determining target regions of the photomultiplier tubes based on positions of the photomultiplier tubes, respectively, obtaining an energy spectrum of each of the photomultiplier tubes based on the background data corresponding to the interaction positions that fall within the target region of each of the photomultiplier tubes, and calibrating a relative gain of each of the photomultiplier tubes based on the corresponding energy spectrum.

The invention relates to the technical field of aerospace optical device packaging, in particular to an anti-irradiation photo-thermal dual-curing conductive adhesive and a preparation method thereof. Comprising the following components in parts by weight: 10-30 parts of epoxy resin, 1-5 parts of a thermal initiator, 2-4 parts of a photoinitiator, 30-75 parts of modified powder, 0-3 parts of a coupling agent, 5-10 parts of an epoxy reactive diluent and 0-10 parts of a flame retardant, the modified powder is prepared by modifying a mixture of a conductive filler, a metallic carbon nanotube and a nano metal oxide by using a modifier. According to the conductive adhesive, the modified powder is added into the conductive adhesive, so that the problem of compatibility of a formula can be solved, warping of the conductive adhesive is effectively reduced, the conductivity of the conductive adhesive is also improved, and meanwhile, the metallic carbon nanotubes form a coaxial circular tube structure by carbon atoms arranged in a hexagonal manner, so that cosmic rays can be absorbed, and the conductivity of the conductive adhesive is improved. The conductive filler and the nano metal oxide powder can fill the gaps between the circular tubes and form a compact structure, and radiation particles can be effectively blocked, so that the radiation resistance of the conductive adhesive is remarkably improved, and the durability and reliability of the optical module in a starry sky environment are greatly improved under the condition of ensuring chip packaging and bonding.

The invention discloses a dense star field cosmic ray identification method fusing multi-scale linear attention. The method comprises the following steps: acquiring a to-be-detected dense star field image and a trained dense star field cosmic ray identification model; to-be-detected dense star field image data are input into the encoding stage and processed in the encoding stage, and output subjected to maximum pooling operation in the encoding stage is obtained; taking the output subjected to the maximum pooling operation in the coding stage as the input of the neck stage, and processing in the neck stage to obtain the output of the neck stage; the output of the neck stage is used as the input of the transpose convolution operation of the decoding stage and the input of the multi-head self-attention mechanism, and the output of the transpose convolution operation, the output of the multi-head self-attention mechanism and the output of the LSK module in the coding stage are spliced to be used as the input of the first convolution block operation of the decoding stage; and the classification mask result of the to-be-detected dense star field image is output after the processing of a second first convolution block and a second convolution block in the decoding stage. According to the method, high detection precision can be kept in a high-density galaxy region, and the robustness of the method in a complex observation scene is highlighted.

The invention discloses a cosmic ray shower muon navigation positioning point feature extraction method, and relates to the technical field of navigation guidance and control, and the method comprises the steps: S1, accumulating and collecting muon data penetrating into a navigation region through an upper particle detector and a lower particle detector in a closed navigation region, and carrying out the time sequence denoising and spatial filtering, so as to obtain a cosmic ray shower muon navigation positioning point feature extraction result; obtaining muon data for efficient imaging; s2, constructing a projection horizontal plane in the closed navigation area, dividing the projection horizontal plane into grids, and determining the number of muons arranged in each cell of the grids in a penetrating manner and the positions of penetrating points of the muons; identifying muons influencing imaging in possible abnormal muons in each cell and deleting the muons; s3, re-estimating the muon distribution density in each cell on the projection horizontal plane, and generating a navigation area color thermodynamic diagram through normalization and color mapping; according to the method, visual, clear and efficient color thermodynamic diagram imaging of a navigation positioning hot spot area is realized, the processing difficulty of a muon navigation positioning diagram is reduced, and the recognition efficiency and reliability of navigation positioning feature points are ensured.