Three-Dimensional Ground-Based Measurements of Urban Air Quality to Evaluate Satellite Derived Interpretations for Urban Air Pollution

Urban air quality and meteorological measurements were carried out in the region of Brescia (Italy) simultaneously to the acquisition of satellite data during winter and summer smog conditions in 1999. The main objectives of the campaigns were: delivery of data for the validation of air pollution interpretations based on satellite imagery, and determination of the aerosol optical thickness in spectral ranges similar to those used by satellites. During the winter campaign the ground-based network was complemented by local stations and by SODAR, DOAS, and FTIR remote sensing measurements. Size distributions of aerosol particles up to 4,000 m a.s.l. were measured by means of an ultra-light aircraft, which was also equipped with meteorological sensors and an ozone sensor. During the summer campaign an interference filter actinometer, an integrating nephelometer and an ozone LIDAR were operated additionally. The satellite images acquired and processed were taken from SPOT. Optical thickness retrieved from interference filter actinometer measurements were compared with the retrievals from the satellite imagery in the same spectral intervals. It is concluded that remaining aerosols in the reference image yield an off-set in the satellite retrieval data and that information about the vertical structure of the boundary layer is very important.     

高温烟火导致直升机坠毁分析

介绍了一架直升机在执行森林灭火任务时坠毁的事故经过和调查过程,并进行了原因分析,认为导致事故发生的罪魁祸首是火场上空的高温烟火.在此基础上论述了高温烟火对直升机的危害,提出了直升机在火场环境中的飞行防护对策.     

飞机起落架支柱固定螺栓环境氢脆断裂研究

某飞机起落架缓冲支柱固定螺栓长期使用后断裂.为了确定该螺栓断裂的原因,对断裂螺栓进行了外观检查,断口宏观、微观分析,能谱仪成分分析,金相组织检查、硬度检测以及氢含量测定,结果表明:断裂螺栓的断口具有氢脆断裂特征,其断裂失效性质为环境氢脆断裂;飞机服役期间,螺栓保护不良,致使环境对螺栓造成了腐蚀,腐蚀产生的氢进入螺栓是导致螺栓产生环境氢脆裂纹的根本原因.对螺栓进行保护可有效地避免该类故障的重复发生.     

某型飞机减速板钛合金梁断裂原因分析

简要介绍了某型飞机减速板钛合金梁断裂的情况。采用XL30场发射环境扫描电镜及能谱仪对断口进行了取样分析。结果表明,在减速板钛合金梁销钉孔周围的应力集中区存在点蚀坑。点蚀坑主要是由于在疲劳载荷和CL-的共同作用下,销钉孔周围的应力集中区表面氧化膜破裂和重新生成的不断交替发生而形成的。在疲劳载荷作用下点蚀坑萌生疲劳裂纹源,并逐渐扩展,最终导致结构破坏。     

华北地区典型机场清单建立及空气质量影响

基于利用AMDAR数据确定大气混合层高度进而对飞机不同工作状态下的时间进行修正的计算方法，核算了2017年华北地区6座典型机场大气污染物排放量.结果显示，6座机场NO_x、CO、VOC、SO₂与PM_2.5的排放总量分别为21504.2，7074.8，1424.0，1283.6和323.2t.飞机源NO_x、CO、VOC与SO₂的排放量远高于机场内其他污染源，而对PM_2.5的排放贡献相差较小.HC与CO的排放主要集中在滑行阶段，占比分别为90.6%与90.2%，而NO_x、SO₂与PM_2.5的排放主要集中在爬升阶段，排放占比分别为58.9%、38.7%和43.5%.6座机场1月份污染物排放量较低，在8月份达到峰值.基于本研究建立的天津滨海国际机场大气污染物排放清单，利用WRF-CAMQ模型研究机场排放对周边区域PM_2.5浓度的影响.结果表明机场区域小时最大贡献浓度为3.24μg/m³；距离机场5km处的年均贡献浓度与小时最大贡献浓度分别为0.08和2.84μg/m³.     

沿海飞机铝合金结构腐蚀与防护

依据地处沿海的19架飞机受海洋大气和海水影响的腐蚀形态和防护方法的调查,分析研究了铝合金结构的腐蚀机理．探寻其腐蚀规律。针对飞机结构设计中的不足,采取了减少电位差、绝缘电极、隔离盐雾海水、减少结构缝隙、增加保护层抗蚀能力的改进防护措施．为飞机设计和维修提供了参考。     

中国华北地区冬季大气污染物航空测量(I)—空中气态污染物污染特征研究

为掌握致酸大气污染物SO₂和NO_x的空间浓度分布,并探讨上述污染物扩散、迁移和传输规律,进而研究其在酸性降水形成过程中的作用,在“八五”期间酸性降水的研究中,针对中国华北地区城市和工业集中以及S0₂和NO_x等酸性大气污染物排放量大的特点,以石家庄及其以东地区为飞行区域,进行了华北地区冬季空中S0₂和NO_x污染特征的航空测量。通过测定发现在华北地区1.5km左右的空中存在着S0₂和NO_x高浓度污染空域,同时S0₂存在着高浓度汇集区。      

Strategy and management for the recycling of carbon fiber-reinforced polymers (CFRPs) in the aircraft industry: a critical review

ABSTRACT

Carbon fiber-reinforced polymers (CFRPs) have attracted attention from the aerospace industry due to their light weight, excellent mechanical properties, and resistance to corrosion. However, CFRP composites are difficult to recycle as their recycling process must be performed under extreme conditions; end-of-life regulations do not directly address the problem with reusing these composites. Thus, the objective of this study is to explore solutions that minimize the use of CFRPs and prolong their useful life in the airline industry. To achieve this goal, this work conducted a review of the state of the art of CFRP fiber recycling, emphasizing the recycling processes, restrictions, and regulations. One solution is to develop a CFRP recycling market that would allow the sequential use of recycled materials among industries in descending order of the required structural performance of the composite.     

北京地区3500m高空内污染物的时空分布特征

利用2007~2010年北京地区3500m高空内飞机探测的大气污染物(NOx、SO2 、CO和O3)数据资料,分析其时空分布特征.结果表明: 在4~11月期间,NOx、SO2和CO月均值有比较明显的一致性变化规律,NOx、SO2 和CO月均值随高度增加而减小,而O3月均值随高度增加,出现先增大后减小的变化规律.温度较高月份(7~10月)值较小,而温度较低月份(4~6月、11月)值较大,但O3月均值季节变化规律为夏季5~9月的较大,春秋季4月、10~11月的较小.不同的高度大气污染物浓度白天逐时变化并不一致,其变化率是1500m以下的比1500~3500m的明显高.北京地区大气污染物区域分布特征是,除城区四环明显较高外,城区正北面、西南面(北京-保定方向)、东南面(北京-天津方向)较高,西北面(北京-张家口方向)较低.     

基于不确定语言的飞机结冰防御系统能力评估

为解决飞机结冰防御系统能力评估中不确定因素较多导致结果不准确的问题,提出基于不确定语言的评估方法。在介绍区间数和语言评估标度的基础上,给出将语言评估标度转化为区间数的方法,并阐述不确定语言变量的定义及运算法则。建立飞机结冰防御系统能力评估指标体系,采用区间数特征向量法确定各指标的区间数权重,并利用区间集结(IA)算子和区间加权矢量和法实现指标的聚合。最后,分析某飞机结冰防御系统,以区间数评估其结冰防御能力。