44 results about "Weather simulation" patented technology

The invention discloses a city weather simulation prediction method based on an improved mesoscale WRF model, and the method comprises the steps: obtaining geographic space information data, carrying out the preprocessing, coupling local climate partitioning and population density grading, carrying out the detailed division of a built earth surface, carrying out the classification conversion of a natural earth surface according to a butt-joint mapping relation, and carrying out the prediction of the natural earth surface. The method comprises the following steps: obtaining a land cover classification data set and calculating to obtain corresponding urban canopy parameters, then improving default underlying surface data built in a mesoscale WRF model, and performing simulation prediction on urban meteorology by using the improved mesoscale WRF model. According to the method, through detailed division of the built-up surface and classification conversion of the natural surface, a surface coverage fine classification data set conforming to the real condition and considering the complex non-uniformity of the built-up area and corresponding city canopy parameters are constructed, then default underlying surface data built in the mesoscale WRF model are improved, and the city meteorological simulation prediction capability is remarkably improved.

The invention relates to a distribution network line multi-class image defect detection method and device based on small sample learning, and relates to the field of distribution network lines. The method comprises the following steps: firstly, acquiring a distribution network line historical inspection image to form a first inspection data set; extracting depth and illumination information of the image in the first data set, and generating a preliminary weather simulation diagram in combination with a physical heuristic synthesis algorithm; inputting the initial weather simulation diagram into a pre-training generative adversarial network to obtain a second inspection data set containing various weather scenes; constructing a third inspection data set by using the first data set and the second data set, and dividing a training data set and a verification data set from the third inspection data set, the third inspection data set and the third inspection data set; training a deep learning model by using the training set and the verification set to obtain a trained defect detection model; and finally, inputting a distribution network line inspection image obtained in real time into the trained model, and outputting a defect detection result. Compared with the prior art, the method has the advantages of improving timeliness and accuracy of distribution network line defect identification and the like.

The invention relates to a method for cross-view geographic positioning of an unmanned aerial vehicle in severe weather. According to the method, a ConvNeXt-based twin network framework is provided for the matching challenge of an unmanned aerial vehicle and a satellite image under a severe weather condition, so that the positioning capability of the network under complex weather is improved. By introducing the weather simulation module, the network can adapt to view angle changes in severe weather such as rain, fog, snow and the like. According to the method, a local mode network and a direction attention module are utilized, and environment information and multi-direction context information are combined, so that the extraction capability of the network on characteristics under cross-view and different weather conditions is enhanced. Besides, in order to improve the robustness of the features under different view angles, a multi-branch feature fusion strategy is adopted, and fused feature vectors are spliced through a classifier. And finally, rapid matching of the unmanned aerial vehicle image and the satellite image is realized by using the constructed geotag database, and the positioning precision in GNSS denial and severe weather environments is effectively improved. Compared with the prior art, the method has higher robustness and accuracy in a complex environment.

The invention proposes a three-dimensional modeling method based on multi-view image fusion and AI semantic material decoupling, and the method comprises the steps: employing a self-adaptive overlapped region weighted fusion strategy in an image preprocessing stage through an improved pyramid block matching algorithm, dynamically adjusting the gray value of a pixel through an inverse distance weighting function, and carrying out the dynamic adjustment of the gray value of the pixel; exposure differences and splicing gaps among multi-view images are eliminated, building structure features are extracted through a graph convolutional network by constructing a two-channel deep learning network and a space geometric channel, semantic segmentation of eaves and beam column components is achieved, and in the two-channel deep learning network, a material decoupling channel adopts an adversarial generative network; according to the method, the texture alignment precision can be improved to 0.3 pixel level in an ancient building digital case, the material attribute restoration error is lower than 8%, the model is supported to directly perform weathering simulation and virtual restoration operation in a Unity / Unreal engine, and a new technical normal form is provided for digital protection and activation utilization of cultural heritage.

The utility model discloses a quality detection device for automobile shock absorber machining, and relates to the technical field of automobile shock absorber machining, the quality detection device comprises a detection box body and a water tank, and further comprises a weather simulation assembly, and the weather simulation assembly comprises a heated assembly and a cooling assembly; the heated assembly comprises a heater fixed outside the detection box body, and the air outlet end of the heater penetrates into the detection box body through an air outlet pipe and then is fixedly communicated with a runway heating ring; the cooling assembly comprises a nitrogen cylinder fixed outside the detection box body, and the gas outlet end of the nitrogen cylinder penetrates into the detection box body through a gas outlet pipe and then is fixedly communicated with a runway cooling ring; the problems that in the prior art, when the sealing performance of the automobile shock absorber is detected at normal temperature, an automobile may run in an extreme weather environment such as an extreme high-temperature environment and an extreme low-temperature environment in an actual situation, so that the extreme environment temperature needs to be simulated when the automobile shock absorber is detected, and the detection time is shortened are solved. And the problem of detecting the automobile shock absorber is solved.

The invention relates to the technical field of weather three-dimensional simulation, in particular to a three-dimensional dynamic simulation method and system based on multi-modal weather data. The method comprises the following steps: acquiring multi-modal meteorological observation data including ground observation station information, radar observation information and satellite observation information, and calculating a time difference value between observation time of each data source; taking the ratio of the time difference value to the spatial distance between the key observation points as a disturbance propagation speed; establishing a space-time correlation window based on the disturbance propagation speed, calculating a deviation correlation coefficient between the observation sources in the space-time correlation window, and judging an atmospheric state type through the deviation correlation coefficient; and mapping the atmospheric state type into a multi-source coordination parameter. According to the method, a proper range can be set according to propagation characteristics of a weather system through the space-time correlation window, observation data intensive with physical consistency is realized, and the problem of dislocation of different observation source data on timestamps or coverage ranges is effectively avoided.

The invention discloses an image depth completion method in a foggy day scene, and the method comprises the steps: 1, collecting image data through employing a camera, and collecting point cloud information through employing a laser radar, and generating a sparse depth map; 2, establishing a foggy weather atmospheric scattering model, and generating a foggy weather simulation image set by using a randomly generated extinction coefficient; 3, building a convolutional neural network, training by using the foggy day simulation image set to obtain an extinction coefficient prediction network model, and outputting the extinction coefficient of the foggy day image; and 4, constructing a double-branch trunk depth completion network, and inputting the foggy day image and the sparse depth map into the depth completion network for processing and fusion to generate a dense depth map. According to the method, the dense depth map can be generated through image depth completion, so that the applicability and effectiveness of depth information are enhanced, and the depth map can be utilized in more applications.

This invention discloses a method for synthesizing severe weather lidar point clouds by combining real priors with geometrically guided intensity generation. First, a weather simulation module is used to convert clear weather data into pseudo-severe weather data with physical constraints from the statistical regularities of real datasets, constructing a high-quality training set. Then, using a structure-intensity decomposition diffusion model, a high-fidelity geometric structure is generated first through an asymmetric conditional diffusion process, and then matching reflection intensity information is generated based on the structure. This method effectively overcomes the modeling difficulties caused by geometry-intensity coupling in existing technologies, and achieves high-fidelity severe weather point cloud synthesis in the absence of large-scale real data.

The utility model relates to the technical field of concrete detection, and provides a road and bridge engineering concrete pavement abrasion experiment device which comprises a supporting frame and a protection plate arranged outside the supporting frame, a square through hole is formed in the center of the top of the supporting frame, and axle supporting plates are arranged on the two sides of the square through hole respectively. The input end and the output end of the speed reducer are respectively connected with the output end of the motor and the axle of the simulation wheel, the bottom of the support frame is provided with a hydraulic cylinder, the output end of the hydraulic cylinder is provided with a support plate, the support plate is provided with a locking assembly for fixing a concrete pavement test block, and the hydraulic cylinder drives the concrete pavement test block to pass through a square through hole of the support frame for experiment. The top and the back of the support frame are respectively provided with a high-temperature simulation assembly and a rainy weather simulation assembly. According to the utility model, the simulated wheel can be attached to the concrete pavement test block for multiple times, and meanwhile, the abrasion condition of the concrete pavement in high-temperature and rainy weather can be simulated, so that the experiment precision is improved.

The invention discloses a solar simulator for a light aging test, and belongs to the technical field of illumination testing, the solar simulator comprises a test board and a universal adjusting support used for adjusting the illumination angle of a daylight illumination system, the top end of the test board is provided with a test photovoltaic panel through a support, and the two sides of the test photovoltaic panel are both provided with amplification assemblies; an air temperature simulation box is arranged on the outer side of the test photovoltaic panel, the air temperature simulation box is rotationally connected with a simulation cover through an electric hinge, a weather simulation mechanism is arranged on the end face of the simulation cover, and optical measurement assemblies are arranged on the two sides of the weather simulation mechanism. Through the arrangement of the electromagnetic base and the switching assembly, the illumination system, the temperature system and the weather system can be synchronously regulated and controlled through single current input of the daylight illumination system, complex electronic control is replaced by mechanical linkage, the fault rate is reduced, the single change of current input can meet the dynamic change of each working condition in the long-time light aging test process, and the test efficiency is improved. And the dynamic working condition switching is ensured without manual intervention.

The invention discloses an unmanned aerial vehicle visual scene simulation device and method based on programmed generation, and relates to the field of man-machine testing and testing. The problems that an existing unmanned aerial vehicle visual simulation platform is single in simulation scene, complex in scene construction, lack of self-defined weather simulation and the like are solved. The device comprises a data reading and preprocessing module used for reading real scene data, preprocessing the data and outputting basic terrain model data and open source street map data; the terrain generation module is used for generating a virtual terrain; the city generation module is used for realizing the construction of a virtual city environment according to the city data and the city element composition method; the object generation module is used for acquiring a generation range and object type parameters specified by a user and generating a model required by the user; and the weather generation module is used for adding a self-defined weather simulation environment model in the constructed virtual city environment and setting a delay event to realize a self-defined weather simulation function. The method is also suitable for the field of complex unmanned aerial vehicle visual simulation scenes.

The system according to this embodiment aims to propose the optimal route for avoiding disaster risks. [Solution] The system according to the embodiment comprises a reception unit, a data collection unit, and an analysis unit. The reception unit receives destination input from the user. The data collection unit collects traffic information and weather simulation results based on the information received by the reception unit. The analysis unit analyzes the data collected by the data collection unit and proposes the optimal route to avoid disaster risks.

The application relates to an airport data dynamic management method, system, computer equipment and storage medium. The method can be applied to cloud technology and intelligent transportation and the like application scenarios, and the method comprises the following steps: in response to a display operation triggered on a management platform page, a visual airport space model is displayed; in response to a weather simulation operation of the airport space model, airport environment data and meteorological data are acquired; a weather simulation model is generated according to the airport environment data and the meteorological data; the weather simulation model is fused into the airport space model for display, and the airport environment data and the meteorological data are displayed; when it is determined that an airport environment state meets preset abnormal conditions based on the airport space model fused with the weather simulation model, the airport environment data and the meteorological data, an abnormal treatment scheme is determined according to the airport environment state. The method can improve the management efficiency of the airport data.

A method is provided for transforming a high-level language representation of a tensor computation graph into a low level language. The method includes assigning a tensor shape and a loop primitive. The method also includes generating, from the tensor computation graph and the assigned loop primitives, an initial loop structure. The method further includes positioning the layers of the tensor computation graph within a nested loop structure to provide a final loop structure, collapsing loops in the final loop structure, and mapping the collapsed loops to hardware components configured to execute the collapsed loops. The method can be applied to artificial intelligence (AI) and machine learning (ML) use cases for improved optimization of neural networks including compilation optimization for improving performance of simulations such as medical simulations, healthcare simulations, weather simulations, and / or simulations related to other complex systems, which can also support decision making.

The invention discloses a multi-factor coupling environment simulation device for testing concrete durability, and belongs to the technical field of concrete durability detection. Comprising a device shell, a sliding partition plate is arranged in the device shell and divides the inner space of the device shell into an upper cavity and a lower cavity, a plurality of telescopic assemblies are arranged in the upper cavity, one ends of the telescopic assemblies are fixed to the sliding partition plate, and the other ends of the telescopic assemblies are fixed to the upper end of the device shell; an annular mounting plate is arranged at the upper part of the edge of the upper surface of the sliding partition plate, a temperature simulation assembly, a humidity simulation assembly and a weathering simulation assembly are arranged above the annular mounting plate, and a through hole for placing a concrete test piece is formed in the middle of the sliding partition plate. The technical scheme is used for solving the problems that the environmental factor simulation of a concrete durability device in the prior art is single, and the working scene of a concrete test piece cannot be simulated.

The present invention discloses a rock weathering simulation system under extreme Martian environments. The system comprises a vacuum chamber, a storage structure, a temperature simulation unit, a gas circulation simulation unit, a wind speed simulation unit, and a light simulation unit. The present invention also discloses a rock weathering simulation test method under extreme Martian environments. Compared with the prior art, the rock weathering simulation system under extreme Martian environments prepared by the present invention can simultaneously simulate extreme environments such as the vacuum, atmospheric, temperature, light, and dust environments on the Martian surface. It monitors changes in the sample's mass, porosity, and surface deformation during weathering under the simulated Martian extreme environment, and systematically evaluates the sample's weathering characteristics.

The invention discloses a rock weathering simulation system in an extreme environment of Mars. The rock weathering simulation system in the extreme environment of Mars comprises a vacuum chamber, a storage structure, a temperature simulation unit, a gas circulation simulation unit, a wind speed simulation unit and an illumination simulation unit. The invention further discloses a rock weathering simulation test method in the extreme environment of Mars. Compared with the prior art, the rock weathering simulation system under the Mars extreme environment can synchronously simulate extreme environments such as a vacuum environment, an atmospheric environment, a temperature environment, an illumination environment and a sand and dust environment on the surface of Mars; and monitoring the changes of the quality, porosity, surface deformation and the like of the sample in the weathering process under the Mars extreme environment of the simulation system, and systematically evaluating the weathering characteristics of the sample.

The present invention relates to a multi-level and multi-granularity simulation method for electromagnetic environment signals for radio frequency detectors. First, a radiation source simulation model, a scattering source simulation model, an interference simulation model, and a transmission weather simulation model for electromagnetic environment signal simulation are established respectively. The radiation source simulation model, the interference simulation model, and the transmission weather simulation model constitute a radiation source simulation subsystem. The scattering source simulation model, the interference simulation model, and the transmission weather simulation model constitute a scattering source simulation subsystem. The radiation source simulation subsystem and the scattering source simulation subsystem, as application software, run on a simulation basic platform to realize the performance simulation test interaction for radio frequency detectors. According to the real-time emission signal and motion attitude of the radio frequency detector, the radiation source simulation subsystem and the scattering source simulation subsystem output to the radio frequency detector for complex electromagnetic environment performance simulation tests, providing support for the performance simulation tests of radio frequency detectors. The simulation efficiency is high and the application prospect is broad.

The application relates to the technical field of automatic driving, in particular to an automatic driving interactive test scene generation device, method, equipment and medium, wherein the device comprises: an extender used for decomposing and supplementing a target natural language description to generate a plurality of scene descriptions; a weather simulator used for simulating a scene according to weather information to generate weather parameters; a self-vehicle locator used for searching a plurality of self-vehicle generated positions on a preset map according to a self-vehicle position; an adversarial vehicle locator used for searching a plurality of adversarial vehicle static positions on the preset map according to an adversarial vehicle relative position and the self-vehicle position; a behavior generator used for constructing a behavior topology network according to an interactive behavior library to generate a plurality of interactive dynamic behaviors; and a scene generation module used for constructing a plurality of comprehensive test scenes according to the related data obtained above. Thus, the problem that the matching degree of the interactivity of scene generation and user demand in the prior art is obviously defective is solved.

The invention relates to a weather simulation method and device for three-dimensional simulation of an open-air plant, and the method comprises the following steps: building a three-dimensional scene of the open-air plant through a computer graphic algorithm according to the actual layout of an object in the open-air plant; creating a model of virtual particles in the three-dimensional scene, wherein the virtual particles comprise raindrop particles and snowflake particles; virtual particles are distributed in the whole domain of the three-dimensional scene, and the virtual particles in a visible area are dynamically activated and rendered according to the visual angle of an observer; based on a ray detection method, intersection point detection is carried out on each falling virtual particle and an object in the scene, the falling point position of the virtual particle is judged, and the motion state of the virtual particle is controlled according to the falling point position; the multi-parameter motion control system is configured for the raindrop particles and the snowflake particles to control the motion postures of the raindrop particles and the snowflake particles in the falling process, the motion state of virtual particles can be simulated in a three-dimensional scene, and the problem that weather simulation is not real in the prior art is solved.

The invention provides an automatic driving system fusion perception test device and method. The test device comprises a road simulation site, a brightness adjusting structure, a weather simulation structure and a control device. The control device is electrically connected with the brightness adjusting structure, the weather simulation structure and the to-be-tested automatic driving system, and is used for receiving a test requirement of the to-be-tested automatic driving system, controlling the brightness adjusting structure to carry out brightness adjustment according to a preset test rule, and controlling the weather simulation structure to carry out weather simulation so as to form a plurality of simulation test scenes; and receiving identification results of the to-be-tested automatic driving system on the test target object in each simulation test scene through an image identification function and a laser radar cloud picture identification function, and determining a score of the to-be-tested automatic driving system according to a preset scoring rule. The invention provides an automatic driving system fusion perception test device and method, and aims to solve the problem that the identification capability of an automatic driving system of a vehicle is inconvenient to evaluate or test in the prior art.

The invention relates to the technical field of railway sand table models, in particular to a BIM-based railway sand table model three-dimensional visualization system, which comprises a data acquisition module, a collaborative modeling module, a weather simulation module, an interaction module, a data management module and a fault diagnosis module. According to the system, key node information is extracted through image recognition and data driving, modeling precision is optimized, multi-line collaborative modeling and linkage are achieved through a uniform interface, weather simulation is built in to analyze extreme environmental influences, multi-view switching and intelligent navigation functions are provided, and real-time data updating and exception handling are supported. According to the method, the three-dimensional modeling precision, the cooperation capability and the user interaction experience can be remarkably improved, and comprehensive technical support is provided for railway design optimization, risk assessment and training demonstration.

The invention discloses a scene test system and method, a storage medium and a computer program product, and the system comprises a mobile platform which is used for moving according to a moving instruction; the at least one cantilever system is used for transmitting a suspended target object according to the steering instruction; the meteorological simulation system is used for constructing a meteorological environment where the tested object is located according to the meteorological simulation instruction; and the control system is used for controlling the mobile platform to execute a moving action, and / or controlling the cantilever system to execute a steering action, and / or controlling the meteorological simulation system to execute a meteorological simulation action according to scene control parameters and / or a target track of the target object. And test site requirements are reduced.

The invention relates to a flight area simulation driving training system which comprises a stereoscopic screen display system, a driving operation table and a flight area simulation driving training management server. The stereoscopic screen display system is matched with a computer host, an integrated display, a video image acquisition module, an intelligent voice recognition module, a weather simulation module and a scoring model; the driving operation table comprises a command controller, a steering wheel, a brake pedal, an accelerator pedal, a gearbox, a base seat and a hand brake. The system constructs a flight area virtual scene based on a three-dimensional digital twinning technology, covers elements such as airport landforms, road networks, aircrafts and working vehicles, and realizes high-precision driving simulation through multi-module cooperation. The real driving environment of the flight area can be simulated in all directions, the driver training efficiency and safety are improved, and the practical operation risk is reduced.

The invention discloses integrated lightning impulse experiment equipment, which comprises an inspection shell, a base, a conveying assembly, a lightning generation device, a response assembly, a drainage grounding assembly and a weather simulation assembly, and is characterized in that the inspection shell is arranged around the base, and an open input port and an open output port are formed in the inspection shell; the conveying assembly is arranged at the two ends of the base and is close to the input port and the output port respectively, a concave inspection groove is formed in the middle of the base, the response assembly is telescopically arranged in the inspection groove, the drainage grounding assembly is arranged at the bottom of the response assembly and is grounded through the base, and the thunder and lightning generation device and the weather simulation assembly are arranged on the inner wall of the inspection shell. According to the integrated lightning impulse experiment equipment, the sample can be conveyed to the response assembly through the conveying assembly, various physical properties of the sample under lightning impulse can be detected, particularly the impact resistance and crushing resistance of the sample can be detected, and a road construction method suitable for a special section can be screened out through experiments.

The invention relates to the technical field of weather simulation, and discloses a virtual weather simulation optimization system based on an unreal engine, which comprises a data acquisition module for acquiring meteorological big data in real time and performing data processing, feature extraction and multi-source data fusion in a data processing module, and a user input module for providing rich interaction functions for a user, the scene generation module supports three-dimensional scene modeling and customizes meteorological element features and scene parameters, the meteorological simulation module simulates an actual weather phenomenon based on meteorological data, the scene adaptation module intelligently fuses features such as weather, natural landscapes and terrains and generates a specific meteorological effect, and the video output module provides a comprehensive playback function. And the feedback optimization module collects user feedback, adjusts system parameters based on machine learning, and continuously optimizes the system performance in cooperation with the performance optimization module. The advanced rendering and simulation functions of the unreal engine are deeply integrated, the high-fidelity and dynamically-changing virtual weather effect is achieved, the reality sense of simulation and the immersion sense of a user are effectively improved, meanwhile, diversified application requirements are met, and the method has wide application prospects.

The utility model relates to the technical field of tire testing equipment, in particular to an all-weather simulation environment box for light truck tires in winter and rainy seasons, which comprises a box body and a simulation tire, a rotating shaft is horizontally and rotatably mounted in the box body, a round block is fixedly mounted at one end of the rotating shaft, and a mounting cavity is formed in the round block; a plurality of through holes are circumferentially formed in the surface of the circular block, rotating rods are horizontally and rotatably mounted in the through holes, touch plates are fixedly connected to the rotating rods in a sleeving manner, and a transmission part used for controlling the rotating rods to rotate together is arranged on the surface of the circular block. Common uneven road conditions in winter and rain seasons can be truly restored, multiple systems work cooperatively, complex climate and road condition environments in winter and rain seasons are simulated in an omnibearing mode, tire testing is closer to actual use scenes, and reliability and practicability of testing results are improved.

The invention relates to the technical field of automatic driving, in particular to an automatic driving interactive test scene generation device, method and equipment and a medium, and the device comprises an expanding and writing device which is used for decomposing and supplementing a target natural language description to generate a plurality of scene descriptions; the weather simulator is used for performing scene simulation according to the weather information to generate weather parameters; the self-vehicle positioner is used for searching a plurality of self-vehicle generation positions on a preset map according to the self-vehicle position; the countermeasure vehicle positioner is used for searching a plurality of countermeasure vehicle static positions on a preset map according to the countermeasure vehicle relative position and the own vehicle position; the behavior generator is used for constructing a behavior topology network according to the interactive behavior library so as to generate a plurality of interactive dynamic behaviors; and the scene generation module is used for constructing a plurality of comprehensive test scenes according to the obtained related data. Therefore, the problem that in the prior art, the interactivity of scene generation and the matching degree with user requirements have obvious defects is solved.

The invention discloses a device for simulating the migration and transformation process of tailings heavy metal and application of the device, and belongs to the mine environment protection simulation research technology. The device comprises a leaching column, a liquid storage system, a weathering simulation system, a collection and detection unit and a data acquisition and control system; release, migration and transformation of heavy metal can be simulated, the simulated weathering system reproduces the natural weathering process of tailings through an adjustable gas flow rate gas supply pump and a porous gas cake, the liquid storage system accurately controls simulated rainfall through a peristaltic pump, and an oxygen sensitive strip monitors the migration path of oxygen in a leaching column in real time. The technical problem that heavy metal migration and conversion in the natural tailing stockpiling environment are difficult to simulate under the laboratory condition is effectively solved, the experimental period is shortened, the experimental precision is improved, the method is suitable for the field of tailing treatment and environment monitoring, and an efficient experimental tool is provided for research on tailing heavy metal migration and conversion.

This invention discloses a multifunctional integrated space physiological countermeasures and movement assistance suit and its control method. The spacesuit includes: a negative pressure fluid regulation system that applies controllable negative pressure to regulate fluid distribution; a biomimetic muscle system that applies controllable torque to simulate muscle exertion; an axial loading system that applies longitudinal compressive stress to simulate bone compression; and a control system that coordinates the operation of each system. In a preferred embodiment, the negative pressure system has multiple sealed zones with the negative pressure value increasing from the head side to the foot side and synchronizing with the cardiac cycle. The biomimetic muscle system can switch between assisted, resistive, and free modes. The axial loading system includes independent subsystems for the cervical spine and trunk-lower limbs. This invention is the first to integrate zoned stepped negative pressure, synchronized cardiac cycle regulation, biomimetic muscle coordination, and graded axial loading into a single wearable system, enabling all-weather simulation of Earth's gravity effects and addressing issues such as head-to-head fluid shift, muscle atrophy, bone loss, and disuse changes in the spine under microgravity.