Small celestial body exploration is of great significance to deep space activities. The dynamics and control of orbits around small celestial bodies is of top priority in the exploration research. It includes the mode...Small celestial body exploration is of great significance to deep space activities. The dynamics and control of orbits around small celestial bodies is of top priority in the exploration research. It includes the modeling of dynamics environment and the orbital dynamics mechanism. This paper introduced state-ofthe-art researches, major challenges, and future trends in this field. Three topics are mainly discussed： the gravitational field modeling of irregular-shaped small celestial bodies, natural orbital dynamics and control, and controlled orbital dynamics. Finally, constructive suggestions are made for China’s future space exploration missions.展开更多
目前,空管各类安全管理信息化平台积累了大量非结构化文本数据,但未得到充分利用,为了挖掘空管不正常事件中潜藏的风险,研究利用收集的四千余条空管站不正常事件数据和自构建的4836个空管领域专业术语词,提出了一个基于空管专业信息词...目前,空管各类安全管理信息化平台积累了大量非结构化文本数据,但未得到充分利用,为了挖掘空管不正常事件中潜藏的风险,研究利用收集的四千余条空管站不正常事件数据和自构建的4836个空管领域专业术语词,提出了一个基于空管专业信息词抽取的双向编码器表征法和双向长短时记忆网络的深度学习模型(Bidirectional Encoder Representations from Transformers-Bidirectional Long Short-Term Memory,BERT-BiLSTM)。该模型通过对不正常事件文本进行信息抽取,过滤其中无用信息,并将双向编码器表征法(Bidirectional Encoder Representations from Transformers,BERT)模型输出的特征向量序列作为双向长短时记忆网络(Bidirectional Long Short-Term Memory,BiLSTM)的输入序列,以对空管不正常事件文本风险识别任务进行对比试验。试验结果显示,在风险识别试验中,基于空管专业信息词抽取的BERT-BiLSTM模型相比于通用领域的BERT模型,风险识别准确率提升了3百分点。可以看出该模型有效提升了空管安全信息处理能力,能够有效识别空管部门日常运行中出现的不正常事件所带来的风险,同时可以为空管安全领域信息挖掘相关任务提供基础参考。展开更多
To study the occurrence mechanism of rock burst during mining the irregular working face,the study took irregular panel 7447 near fault tectonic as an engineering background.The spatial fracture characteristic of over...To study the occurrence mechanism of rock burst during mining the irregular working face,the study took irregular panel 7447 near fault tectonic as an engineering background.The spatial fracture characteristic of overlying strata was analyzed by Winkler elastic foundation beam theory.Furthermore,the influence law of panel width to suspended width and limit breaking span of key strata were also analyzed by thin plate theory.Through micro-seismic monitoring,theoretical analysis,numerical simulation and working resistance of support of field measurement,this study investigated the fracture characteristic of overlying strata and mechanism of rock burst in irregular working face.The results show that the fracture characteristic of overlying strata shows a spatial trapezoid structure,with the main roof being as an undersurface.The fracture form changes from vertical‘‘O-X"type to transverse‘‘O-X"type with the increase of trapezoidal height.From the narrow mining face to the wide mining face,the suspended width of key strata is greater than its limit breaking width,and a strong dynamic load is produced by the fracture of key strata.The numerical simulation and micro-seismic monitoring results show that the initial fracture position of key strata is close to tailgate 7447.Also there is a high static load caused by fault tectonic.The dynamic and static combined load induce rock burst.Accordingly,a cooperative control technology was proposed,which can weaken dynamic load by hard roof directional hydraulic fracture and enhance surrounding rock by supporting system.展开更多
文摘Small celestial body exploration is of great significance to deep space activities. The dynamics and control of orbits around small celestial bodies is of top priority in the exploration research. It includes the modeling of dynamics environment and the orbital dynamics mechanism. This paper introduced state-ofthe-art researches, major challenges, and future trends in this field. Three topics are mainly discussed： the gravitational field modeling of irregular-shaped small celestial bodies, natural orbital dynamics and control, and controlled orbital dynamics. Finally, constructive suggestions are made for China’s future space exploration missions.
文摘目前,空管各类安全管理信息化平台积累了大量非结构化文本数据,但未得到充分利用,为了挖掘空管不正常事件中潜藏的风险,研究利用收集的四千余条空管站不正常事件数据和自构建的4836个空管领域专业术语词,提出了一个基于空管专业信息词抽取的双向编码器表征法和双向长短时记忆网络的深度学习模型(Bidirectional Encoder Representations from Transformers-Bidirectional Long Short-Term Memory,BERT-BiLSTM)。该模型通过对不正常事件文本进行信息抽取,过滤其中无用信息,并将双向编码器表征法(Bidirectional Encoder Representations from Transformers,BERT)模型输出的特征向量序列作为双向长短时记忆网络(Bidirectional Long Short-Term Memory,BiLSTM)的输入序列,以对空管不正常事件文本风险识别任务进行对比试验。试验结果显示,在风险识别试验中,基于空管专业信息词抽取的BERT-BiLSTM模型相比于通用领域的BERT模型,风险识别准确率提升了3百分点。可以看出该模型有效提升了空管安全信息处理能力,能够有效识别空管部门日常运行中出现的不正常事件所带来的风险,同时可以为空管安全领域信息挖掘相关任务提供基础参考。
基金supported by the Key Project of National Natural Science Foundation of China (No. 51634001)the National Natural Science Foundation of China (Nos. 51404269 and 51674253)+1 种基金the State Key Research Development Program of China (No. 2016YFC0801403)the Key Research Development Program of Jiangsu Province, China (No. BE2015040)
文摘To study the occurrence mechanism of rock burst during mining the irregular working face,the study took irregular panel 7447 near fault tectonic as an engineering background.The spatial fracture characteristic of overlying strata was analyzed by Winkler elastic foundation beam theory.Furthermore,the influence law of panel width to suspended width and limit breaking span of key strata were also analyzed by thin plate theory.Through micro-seismic monitoring,theoretical analysis,numerical simulation and working resistance of support of field measurement,this study investigated the fracture characteristic of overlying strata and mechanism of rock burst in irregular working face.The results show that the fracture characteristic of overlying strata shows a spatial trapezoid structure,with the main roof being as an undersurface.The fracture form changes from vertical‘‘O-X"type to transverse‘‘O-X"type with the increase of trapezoidal height.From the narrow mining face to the wide mining face,the suspended width of key strata is greater than its limit breaking width,and a strong dynamic load is produced by the fracture of key strata.The numerical simulation and micro-seismic monitoring results show that the initial fracture position of key strata is close to tailgate 7447.Also there is a high static load caused by fault tectonic.The dynamic and static combined load induce rock burst.Accordingly,a cooperative control technology was proposed,which can weaken dynamic load by hard roof directional hydraulic fracture and enhance surrounding rock by supporting system.
