Chang’e-5 explorer successfully acquired lunar regolith core samples from depths of greater than 1 m of lunar surface.This study analyzed the lunar core drilling process based on the telemetry data,image information,...Chang’e-5 explorer successfully acquired lunar regolith core samples from depths of greater than 1 m of lunar surface.This study analyzed the lunar core drilling process based on the telemetry data,image information,and returned samples to optimize the sampling device design and enhance the understanding of the lunar regolith.In particular,a prediction method for the projected drilling path and local terrain fitting of drilling dip angle was proposed based on the flight events recorded during the core drilling process and the image information acquired before,during,and after sampling.The results revealed that the drilling dip angle of Chang’e-5 was approximately2.3.,and the deviation of the drilling length and depth was less than 2 mm.For continuous drilling,a fusion method based on telemetry data and image information was applied to determine the demarcation point of drilling with and without the lunar soil.The position of the demarcation point implied that the drilling point remained at approximately 6 mm loose soil,thereby lagging the action of the force response.Additionally,a characteristic parameter comparison method was proposed for the lunar and ground drilling to analyze the status of the lunar soil.Furthermore,the analysis results revealed that the majority of the Chang’e-5 drilling samples were derived from 0–73.8 cm below the lunar surface and few samples were extracted below 73.8 cm,as the drilling encountered several rocky regions.Moreover,the drilling point exhibited two prominent stratification variations at~28.7 cm and~70 cm below the lunar surface.Ultimately,the preliminary relationship between sample dissected position in soft tube and drilling displacement was analyzed.The segmented estimation results can support research on subsurface lunar soil.展开更多
Multi-core processor is widely used as the running platform for safety-critical real-time systems such as spacecraft,and various types of real-time tasks are dynamically added at runtime.In order to improve the utiliz...Multi-core processor is widely used as the running platform for safety-critical real-time systems such as spacecraft,and various types of real-time tasks are dynamically added at runtime.In order to improve the utilization of multi-core processors and ensure the real-time performance of the system,it is necessary to adopt a reasonable real-time task allocation method,but the existing methods are only for single-core processors or the performance is too low to be applicable.Aiming at the task allocation problem when mixed real-time tasks are dynamically added,we propose a heuristic mixed real-time task allocation algorithm of virtual utilization VU-WF(Virtual Utilization Worst Fit)in multi-core processor.First,a 4-tuple task model is established to describe the fixedpoint task and the sporadic task in a unified manner.Then,a VDS(Virtual Deferral Server)for serving execution requests of fixed-point task is constructed and a schedulability test of the mixed task set is derived.Finally,combined with the analysis of VDS's capacity,VU-WF is proposed,which selects cores in ascending order of virtual utilization for the schedulability test.Experiments show that the overall performance of VU-WF is better than available algorithms,not only has a good schedulable ratio and load balancing but also has the lowest runtime overhead.In a 4-core processor,compared with available algorithms of the same schedulability ratio,the load balancing is improved by 73.9%,and the runtime overhead is reduced by 38.3%.In addition,we also develop a visual multi-core mixed task scheduling simulator RT-MCSS(open source)to facilitate the design and verification of multi-core scheduling for users.As the high performance,VU-WF can be widely used in resource-constrained and safety-critical real-time systems,such as spacecraft,self-driving cars,industrial robots,etc.展开更多
This study focuses on the physical and chemical properties of surficial lunar regolith(LR)samples returned from the Moon by the Chang’E-5(CE-5)mission.Insights regarding the effect of a new sampling geological site o...This study focuses on the physical and chemical properties of surficial lunar regolith(LR)samples returned from the Moon by the Chang’E-5(CE-5)mission.Insights regarding the effect of a new sampling geological site on the surficial lunar sample CE5 C0400 were illustrated using nondestructive techniques such as laser diffractometry coupled with image analysis,X-ray computed tomography,and field emission scanning electron microscopy equipped with energy dispersive spectroscopy,and Xray diffraction combined with Rietveld refinement.From the characterization analyses,the CE-5 sampling site in the northeastern Oceanus Procellarum on the Moon yields a unique collection of relatively regular-shaped and fine basalt-dominated particles.The median grain size D_(50) is(55.24±0.96)μm,falling within the relatively low end of the range of the Apollo lunar returned samples.The coefficient of uniformity C_(u)of 15.1 and the coefficient of curvature C_(c)of 1.7 could classify CE5 C0400 to be well-graded.The minerals in CE5 C0400 comprise approximately 44.5%pyroxene,30.4%plagioclase,3.6%olivine,and6.0%ilmenite.There is a relatively low content of approximately 15.5%glass phase in the CE-5 lunar sample.From the results,we deduce that the CE-5 LR structure could have mainly resulted from micrometeoroid impacts to achieve such a high level of maturity.展开更多
Periodic control systems （PCSs） are widely used in real-time embedded system domain. However, traditional manual requirement analysis assumes the expert knowledge, which is laborious and error-prone. This paper prop...Periodic control systems （PCSs） are widely used in real-time embedded system domain. However, traditional manual requirement analysis assumes the expert knowledge, which is laborious and error-prone. This paper proposes a novel requirement analysis approach, which supports the automated validation of the informal requirement specifi- cations. Based on the normalized initial requirement docu- ments, our approach can construct an intermediate SPARDL model with both formal syntax and semantics. To check the overall system behaviors, our approach can transform the SPARDL models into executable code for simulation. The derived prototype simulator from SPARDL models enables the testing-based system behavior validation. Moreover, our approach enables the analysis of the dataflow relations in SPARDL models. By revealing input/output and affecting re- lations, our dataflow analysis techniques can help software engineers to figure out the potential data dependencies be- tween SPARDL modules. This is very useful for the module reuse when a new version of the system is developed. A study of our approach using an industry design demonstrates the practicality and effectiveness of our approach.展开更多
Helium-3(3He)is a noble gas that has critical applications in scientific research and promising application potential as clean fusion energy.It is thought that the lunar regolith contains large amounts of helium,but i...Helium-3(3He)is a noble gas that has critical applications in scientific research and promising application potential as clean fusion energy.It is thought that the lunar regolith contains large amounts of helium,but it is challenging to extract because most helium atoms are reserved in defects of crystals or as solid solutions.Here,we find large amounts of helium bubbles in the glassy surface layer of ilmenite particles that were brought back by the Chang’E-5 mission.The special disordered atomic packing structure of glasses should be the critical factor for capturing the noble helium gas.The reserves in bubbles do not require heating to high temperatures to be extracted.Mechanical methods at ambient temperatures can easily break the bubbles.Our results provide insights into the mechanism of helium gathering on the moon and offer guidance on future in situ extraction.展开更多
Finding water resources is a crucial objective of lunar missions.However,both hydroxyl(OH)and natural water(H2O)have been reported to be scarce on the Moon.We propose a potential method for obtaining water on the Moon...Finding water resources is a crucial objective of lunar missions.However,both hydroxyl(OH)and natural water(H2O)have been reported to be scarce on the Moon.We propose a potential method for obtaining water on the Moon through H2O formation via endogenous reactions in lunar regolith(LR),specifically through the reaction FeO/Fe2O3+H/Fe+H2O.This process is demonstrated using LR samples brought back by the Chang’E-5 mission.FeO and Fe2O3 are lunar minerals containing Fe oxides.Hydrogen(H)retained in lunar minerals from the solar wind can be used to produce water.The results of this study reveal that 51–76 mg of H2O can be generated from 1 g of LR after melting at temperatures above 1,200 K.This amount is10,000 times the naturally occurring OH and H2O on the Moon.Among the five primary minerals in LR returned by the Chang’E-5 mission,FeTiO3 ilmenite contains the highest amount of H,owing to its unique lattice structure with sub-nanometer tunnels.For the first time,in situ heating experiments using a transmission electron microscope reveal the concurrent formation of Fe crystals and H2O bubbles.Electron irradiation promotes the endogenous redox reaction,which is helpful for understanding the distribution of OH on the Moon.Our findings suggest that the hydrogen retained in LR is a significant resource for obtaining H2O on the Moon,which is helpful for establishing a scientific research station on the Moon.展开更多
基金supported by the National Medium and Longterm Science and Technology Major Special Project of ChinaYoung Top Talents Foundation of China Aerospace Science and Technology Corporation+1 种基金Pre-research project on Civil Aerospace Technologies by CNSA under Grant D020201the National Natural Science Foundation of China(Research on Supporting Management Strategy of Scientific Research Activities in Lunar Exploration under Grant 42142033)。
文摘Chang’e-5 explorer successfully acquired lunar regolith core samples from depths of greater than 1 m of lunar surface.This study analyzed the lunar core drilling process based on the telemetry data,image information,and returned samples to optimize the sampling device design and enhance the understanding of the lunar regolith.In particular,a prediction method for the projected drilling path and local terrain fitting of drilling dip angle was proposed based on the flight events recorded during the core drilling process and the image information acquired before,during,and after sampling.The results revealed that the drilling dip angle of Chang’e-5 was approximately2.3.,and the deviation of the drilling length and depth was less than 2 mm.For continuous drilling,a fusion method based on telemetry data and image information was applied to determine the demarcation point of drilling with and without the lunar soil.The position of the demarcation point implied that the drilling point remained at approximately 6 mm loose soil,thereby lagging the action of the force response.Additionally,a characteristic parameter comparison method was proposed for the lunar and ground drilling to analyze the status of the lunar soil.Furthermore,the analysis results revealed that the majority of the Chang’e-5 drilling samples were derived from 0–73.8 cm below the lunar surface and few samples were extracted below 73.8 cm,as the drilling encountered several rocky regions.Moreover,the drilling point exhibited two prominent stratification variations at~28.7 cm and~70 cm below the lunar surface.Ultimately,the preliminary relationship between sample dissected position in soft tube and drilling displacement was analyzed.The segmented estimation results can support research on subsurface lunar soil.
文摘Multi-core processor is widely used as the running platform for safety-critical real-time systems such as spacecraft,and various types of real-time tasks are dynamically added at runtime.In order to improve the utilization of multi-core processors and ensure the real-time performance of the system,it is necessary to adopt a reasonable real-time task allocation method,but the existing methods are only for single-core processors or the performance is too low to be applicable.Aiming at the task allocation problem when mixed real-time tasks are dynamically added,we propose a heuristic mixed real-time task allocation algorithm of virtual utilization VU-WF(Virtual Utilization Worst Fit)in multi-core processor.First,a 4-tuple task model is established to describe the fixedpoint task and the sporadic task in a unified manner.Then,a VDS(Virtual Deferral Server)for serving execution requests of fixed-point task is constructed and a schedulability test of the mixed task set is derived.Finally,combined with the analysis of VDS's capacity,VU-WF is proposed,which selects cores in ascending order of virtual utilization for the schedulability test.Experiments show that the overall performance of VU-WF is better than available algorithms,not only has a good schedulable ratio and load balancing but also has the lowest runtime overhead.In a 4-core processor,compared with available algorithms of the same schedulability ratio,the load balancing is improved by 73.9%,and the runtime overhead is reduced by 38.3%.In addition,we also develop a visual multi-core mixed task scheduling simulator RT-MCSS(open source)to facilitate the design and verification of multi-core scheduling for users.As the high performance,VU-WF can be widely used in resource-constrained and safety-critical real-time systems,such as spacecraft,self-driving cars,industrial robots,etc.
文摘This study focuses on the physical and chemical properties of surficial lunar regolith(LR)samples returned from the Moon by the Chang’E-5(CE-5)mission.Insights regarding the effect of a new sampling geological site on the surficial lunar sample CE5 C0400 were illustrated using nondestructive techniques such as laser diffractometry coupled with image analysis,X-ray computed tomography,and field emission scanning electron microscopy equipped with energy dispersive spectroscopy,and Xray diffraction combined with Rietveld refinement.From the characterization analyses,the CE-5 sampling site in the northeastern Oceanus Procellarum on the Moon yields a unique collection of relatively regular-shaped and fine basalt-dominated particles.The median grain size D_(50) is(55.24±0.96)μm,falling within the relatively low end of the range of the Apollo lunar returned samples.The coefficient of uniformity C_(u)of 15.1 and the coefficient of curvature C_(c)of 1.7 could classify CE5 C0400 to be well-graded.The minerals in CE5 C0400 comprise approximately 44.5%pyroxene,30.4%plagioclase,3.6%olivine,and6.0%ilmenite.There is a relatively low content of approximately 15.5%glass phase in the CE-5 lunar sample.From the results,we deduce that the CE-5 LR structure could have mainly resulted from micrometeoroid impacts to achieve such a high level of maturity.
基金Zheng Wang, Bin Gu, and Mengfei Yang are par-tially supported by the National Natural Science Foundation of China （Grant Nos. 90818024, 91118007）. Jianwen Li is partially supported by the National Natural Science Foundation of China （Grant No. 61021004）. Geguang Pu is partially supported by Fundamental Research Funds for the Central Univer- sities, 973 Program （Grant No. 2011CB302904） and the National Natural Science Foundation of China （Grant No. 61061130541）. Mengsong Chen is partially supported by the National Natural Science Foundation of China （Grant No. 61202103）.
文摘Periodic control systems （PCSs） are widely used in real-time embedded system domain. However, traditional manual requirement analysis assumes the expert knowledge, which is laborious and error-prone. This paper proposes a novel requirement analysis approach, which supports the automated validation of the informal requirement specifi- cations. Based on the normalized initial requirement docu- ments, our approach can construct an intermediate SPARDL model with both formal syntax and semantics. To check the overall system behaviors, our approach can transform the SPARDL models into executable code for simulation. The derived prototype simulator from SPARDL models enables the testing-based system behavior validation. Moreover, our approach enables the analysis of the dataflow relations in SPARDL models. By revealing input/output and affecting re- lations, our dataflow analysis techniques can help software engineers to figure out the potential data dependencies be- tween SPARDL modules. This is very useful for the module reuse when a new version of the system is developed. A study of our approach using an industry design demonstrates the practicality and effectiveness of our approach.
基金financial support from National Natural Science Foundation of China(NSFC 51922102,92163108,61888102,11790291)Youth Innovation Promotion Association CAS(2019296)+1 种基金Zhejiang Provincial Natural Science Foundation of China(LZ22A030001,LR22E010004)Ningbo 2025 Science and Technology Innovation Project(2022Z033)are acknowledged.
文摘Helium-3(3He)is a noble gas that has critical applications in scientific research and promising application potential as clean fusion energy.It is thought that the lunar regolith contains large amounts of helium,but it is challenging to extract because most helium atoms are reserved in defects of crystals or as solid solutions.Here,we find large amounts of helium bubbles in the glassy surface layer of ilmenite particles that were brought back by the Chang’E-5 mission.The special disordered atomic packing structure of glasses should be the critical factor for capturing the noble helium gas.The reserves in bubbles do not require heating to high temperatures to be extracted.Mechanical methods at ambient temperatures can easily break the bubbles.Our results provide insights into the mechanism of helium gathering on the moon and offer guidance on future in situ extraction.
基金Financial support from the National Key R&D Program of China(2018YFA0703600)the National Natural Science Foundation of China(NSFC 52222105,51922102,92163108,61888102,and 51827801)+2 种基金the Youth Innovation Promotion Association CAS(2019296)the Zhejiang Provincial Natural Science Foundation of China(LZ22A030001 and LR22E010004)the Ningbo 2025 Science and Technology Innovation Project is acknowledged.
文摘Finding water resources is a crucial objective of lunar missions.However,both hydroxyl(OH)and natural water(H2O)have been reported to be scarce on the Moon.We propose a potential method for obtaining water on the Moon through H2O formation via endogenous reactions in lunar regolith(LR),specifically through the reaction FeO/Fe2O3+H/Fe+H2O.This process is demonstrated using LR samples brought back by the Chang’E-5 mission.FeO and Fe2O3 are lunar minerals containing Fe oxides.Hydrogen(H)retained in lunar minerals from the solar wind can be used to produce water.The results of this study reveal that 51–76 mg of H2O can be generated from 1 g of LR after melting at temperatures above 1,200 K.This amount is10,000 times the naturally occurring OH and H2O on the Moon.Among the five primary minerals in LR returned by the Chang’E-5 mission,FeTiO3 ilmenite contains the highest amount of H,owing to its unique lattice structure with sub-nanometer tunnels.For the first time,in situ heating experiments using a transmission electron microscope reveal the concurrent formation of Fe crystals and H2O bubbles.Electron irradiation promotes the endogenous redox reaction,which is helpful for understanding the distribution of OH on the Moon.Our findings suggest that the hydrogen retained in LR is a significant resource for obtaining H2O on the Moon,which is helpful for establishing a scientific research station on the Moon.
