一种遥感影像快速计算水面率的方法

为了有效去除阴影噪声对遥感影像水体提取的干扰，快速准确计算大区域范围内的水面率，本文提出基于GF6（高分六号卫星）影像，利用UWI（Urban Water Index，城市水体指数）并结合FROM-GLC10（Finer Resolution Observa-tion and Monitoring of Global Land Cover 10，全球陆地覆盖精细化观测与监测10）数据，通过求交计算和小碎斑删除实现水体提取结果的精细化，有效消除了阴影等噪声对水体提取的干扰，实现水面率的快速计算。本文选择中山市作为试验区，试验区域范围广、地物背景复杂，综合对比本文算法、NDWI（Normalized Water Index，归一化水体指数）算法和TSUWI（Two-Sted Urban Water Index，城市二类水体指数）算法，从定性与定量角度分析，结果表明：本文算法提取的水体连续完整、漏提和误提较少，可有效去除阴影、建筑、道路等噪声干扰，在总体精度、Kappa系数、错分误差、漏分误差等指标均取得了较好结果。利用UWI与FROM-GLC10数据相结合计算水面率具有可行性，为工程化、大面积、快速计算水面率提供了一种新的思路。     

选择性激光烧结尼龙材料及其挡水板制件性能研究

采用SLS尼龙12设计并成形了某箭体低承载挡水板薄壁结构,重点就SLS尼龙12及其碳纤维增强材料的力学、热学、断口微观形貌以及制件SLS工艺参数进行了研究。研究表明,选用牌号X1556尼龙12作为挡水板材料,其无缺口冲击强度81.2 kJ/m~2,断裂伸长率26.9%,烧结窗口温度差26.0℃,材料具备良好的抗冲击强度、断裂韧性和较宽的烧结窗口温度范围。优化设置成形工艺参数,如预铺粉起始温度为155℃,预铺粉保持温度168℃,加工温度169℃,填充速度4 000 mm/s,成形的挡水板制件外观良好,并且该制件通过了防水及耐热试验考核验证,为SLS尼龙成形技术在航天领域中的拓展应用打下基础。     

Hardware qualification for scientific ballooning missions

The European Stratospheric Balloon Observatory (ESBO) initiative aims at simplifying the access to stratospheric balloon missions. We plan to provide platforms and support with instrument design in order to support scientists. During the design process, the inevitable question of qualification for the harsh flight conditions arises. Unfortunately, there is no existing standard for qualification of stratospheric ballooning hardware. Thus, we developed a qualification procedure for use within ESBO and similar projects.In this paper, we present our analysis of the environmental conditions in the stratosphere. While conditions at typical balloon float altitudes are similar to the space environment, there are also some relevant differences. For example, the thermal environment is dominated by radiation and thermal conduction, but the remaining atmosphere still supports a certain amount of convection. The remaining atmospheric pressure in the stratosphere also leads to reduced arcing distances. Vibrational loads are far less than for space missions, but quasi-static or shock loads may occur. The criticality of radiation increases with mission duration.Based on the environmental conditions, we present the qualification procedures for ESBO, which are based on the European Cooperation for Space Standardization (ECSS) standards for space systems. Overtesting against too high requirements leads to overengineering, driving mission cost and mitigating the advantages of balloons over space missions. Therefore, we modified the ECSS standards to fit typical scientific ballooning missions over several days at altitudes up to 40 km. Furthermore, we analyzed design rules for space systems with regard to their relevance for scientific ballooning, including material and component selection. We present the experience from the hardware qualification process for the ESBO prototype STUDIO (Stratospheric UV Demonstrator of an Imaging Observatory). Even though boundary conditions are different for each individual mission, we aimed for a broader approach: We investigated more general requirements for scientific ballooning missions to support future flights.