The potential for radiometric retrievals of halocarbon concentrations from the MIPAS-E instrument

Halocarbons, such as CFC-11, CFC-12 and HCFC-22, are important trace gases in the atmosphere through their role as greenhouse gases and their influence on stratospheric ozone chemistry. This paper focuses on an initial study using integration of spectral radiance measurements from a spaceborne limb sounding Fourier Transform Spectrometer (FTS) to retrieve these compounds in the upper troposphere and lower stratosphere (UTLS). The instrument employed in this study is the Michelson Interferometer for Passive Atmospheric Sounding onboard ENVISAT (MIPAS-E) which obtains spectral data in the altitude range of 6–68 km at an unapodized spectral resolution of 0.025 cm⁻¹. We have used optimal estimation techniques to retrieve vertical information for these compounds using a radiometric approach.

It is shown that significant retrieval information is obtained at up to five measured levels in the UTLS for CFC-11, up to six for CFC-12 and up to two levels for HCFC-22. An initial error analysis indicates significant sensitivity of our retrievals to variability in operationally retrieved pressure and temperature data. For each halocarbon, gain, offset and spectroscopic uncertainties generally each contribute less than 10% to the total error. Finally, tracer correlations are used to compare the datasets to equivalent relationships derived here from version 2 ATMOS data with very good agreements for CFC-12 but with more variability in the CFC-11 comparisons.     

Present status of very high energy gamma ray observations

Recent results from observations of the southern sky objects are summarized. The unpulsed, persistent very high energy (VHE) emission from the gamma ray pulsars, the Crab and PSR1706-44, is discussed. A process of energetic electrons ejection may take place from a variety of other objects such as from X-ray binaries, similarly to the pulsars. Such an effect may be seen also in pair halos around extragalactic VHE gamma ray emitters, the observational study of which is still in a preliminary stage in the southern hemisphere.     

DZ125定向凝固高温合金的研究

研究了可用作先进航空发动机定向薄壁空心叶片的DZ125合金,该合金具有高的综合性能,其力学性能水平高于国内外广泛应用的同类商用典型定向合金,同时具有良好的定向铸造工艺性能和高的薄壁力学性能.合金已用于铸造某航空发动机的具有复杂内腔的薄壁定向叶片,并已通过台架试车,投入小批量生产.     

隐身飞机综述

介绍了隐身飞机的发展状况和特点,对美国现役的F-117、B-2和即将服役的F-22以及俄罗斯的米格1.44、苏-35进行了详述,分析了21世纪隐身飞机的发展趋势。     

DZ125带小孔构件低循环/保载疲劳试验与分析

进行了定向结晶合金DZ125带小孔构件在高温下的低循环/保载疲劳试验.此构件试验用来部分模拟航空发动机气膜冷却的空心涡轮转子叶片, 试验方案根据空心涡轮转子叶片的几何特征和所承受的温度及载荷状况来设计.介绍了试验方案和试验结果分析, 包括寿命分析、试验裂纹扩展规律分析和金相分析.结果表明小孔应力集中和保载是构件破坏的主要原因, 孔边电火花加工特征对裂纹萌生起到决定性影响.      

DZ408合金低周疲劳行为

研究了 DZ408合金在950℃,1000℃和1050℃,应变比为0．05条件下的低周疲劳性能。结果表明：平均应变为正时,非对称循环应变控制会产生平均应力松弛现象,且随着温度与应变幅的增大,平均应力松弛速率增大;在950℃,1000℃和1050℃时,材料具有 Massing 特性,采用修正的 SWT 模型能很好地预测不同温度下应变比为0．05的低周疲劳寿命,且给出了修正 SWT 模型参数随温度变化的关系式Δεt 2σmax ＝（－38．9＋0．101 T）N（0．96－0．0014T）。     

美军面向第四代战斗机的数据链建设及启示

介绍美军现役主要战术数据链及美军针对四代机的数据链改进和试验情况,分析美军第四代战斗机的技战术性能,得到美军对下一代数据链建设方向的重点,对我军今后数据链建设具有借鉴意义,从而更有针对性地加强我军的数据链建设,提高我空军的整体战斗力。     

倾转旋翼机设计特点及难点浅析

通过对国外倾转旋翼机的发展历程及具有代表性的V-22"鱼鹰"设计特点进行分析,总结了倾转旋翼类飞机的设计特点及技术难点,并对倾转旋翼机的发展前景进行了展望,为国内此类飞机的研制提供思路和参考。     

非结构网格下可压缩黏性流体的隐式算法

采用牛顿线化和Roe近似Jacobians矩阵隐式算法,实现基于非结构网格的三维定常黏性流动问题的求解.分别对平板、跨声涡轮叶片Mark-Ⅱ和CW-22这三种具有代表性的流动进行数值模拟,并详细分析了流动细节,模拟结果与理论以及实验值吻合良好,准确预测了流场内激波、二次流等重要的流动现象.验证了基于非结构网格的可压缩流体隐式计算方法对于黏性流动问题的计算是正确的.      

DZ125光滑试样与小孔构件低循环/保载疲劳寿命建模

依据定向结晶合金DZ125光滑试样的低循环/保载疲劳试验寿命数据,提出一种预测定向结晶合金低循环/保载疲劳寿命的模型.此寿命模型可以同时考虑材料的晶向、平均应力、应变范围、应变比、最大应力对寿命的影响.接着研究DZ125合金光滑试样低循环/保载疲劳寿命与小孔构件低循环/保载疲劳寿命的关系,提出一种从光滑试样低循环/保载疲劳寿命数据预测小孔构件低循环/保载疲劳寿命的方法.应用本文提出的寿命模型,预测DZ125带小孔构件的低循环/保载疲劳寿命,并将预测寿命与小孔构件试验寿命对比,误差在2倍分散带左右.