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顺德区基础测绘成果保密系统建设
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作者 李太元 柯俊 余爱华 《北京测绘》 2019年第5期588-591,共4页
为响应国家法律法规对基础测绘成果的安全保密要求,通过技术手段加强测绘数据的保密管理,顺德区开展了基础测绘成果保密系统的建设和应用,从实际需求出发,提出系统性的解决方案、技术原理、系统架构和加密流程,通过文件加密、实体加密... 为响应国家法律法规对基础测绘成果的安全保密要求,通过技术手段加强测绘数据的保密管理,顺德区开展了基础测绘成果保密系统的建设和应用,从实际需求出发,提出系统性的解决方案、技术原理、系统架构和加密流程,通过文件加密、实体加密、数字水印等保密手段,为测绘数据生产、加工、存储、应用等环节提供安全保障,在基础测绘成果应用当中起到了很好的保护作用,在测绘地理信息保密工作中具有较好的参考意义。 展开更多
关键词 基础测绘成果 保密系统 实体加密 文件加密 数字水印
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Effects of mask wall angle on matrix-hole shape changes during electrochemical machining by mask 被引量:8
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作者 李冬林 朱荻 +1 位作者 李寒松 刘金国 《Journal of Central South University》 SCIE EI CAS 2011年第4期1115-1120,共6页
The influences of the mask wall angle on the current density distribution,shape of the evolving cavity and machining accuracy were investigated in electrochemical machining(ECM) by mask.A mathematical model was develo... The influences of the mask wall angle on the current density distribution,shape of the evolving cavity and machining accuracy were investigated in electrochemical machining(ECM) by mask.A mathematical model was developed to predict the shape evolution during the ECM by mask.The current density distribution is sensitive to mask wall angle.The evolution of cavity is determined by the current density distribution of evolving workpiece surface.The maximum depth is away from the center of holes machined,which leads to the island appearing at the center of cavity for mask wall angles greater than or equal to 90°(β≥90°).The experimental system was established and the simulation results were experimentally verified.The results indicate that the simulation results of cavity shape are consistent with the actual ones.The experiments also show that the repetition accuracy of matrix-hole for β≥90° is higher than that for β<90°.A hole taper is diminished,and the machining accuracy is improved with the mask wall angle increasing. 展开更多
关键词 electrochemical machining matrix-hole machining accuracy current density distribution
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