Signature of the 11-Year Cycle in the Upper Atmosphere

In the last 45 years I have studied the thermal structure of the atmosphere from the thermosphere down to the stratosphere, and found evidence of its variability in relationship with the change of solar irradiation during the 11-year solar cycle. I would review, in the light of recent model results, the measurements which I had made since the 1960s and which, for some of them, did not find any explanation at the time of their publication. The data were obtained by two different techniques, rockets and lidars and correspond to different regions of the atmosphere from the upper thermosphere to the stratosphere. The expectation was until recently that the atmosphere should be warmed by an increase of solar flux in the course of the solar cycle due to the increase of UV flux. It has been shown to be the case in the tropical stratosphere and at all latitudes in the upper thermosphere. But, at high and mid latitudes and at other altitudes, the reverse situation was found to exist and, until recently, this cooling observed in parts of the atmosphere with increasing solar flux had never been simulated by models. In addition to reviewing our own data, the paper will present recent results using other dataset which support our observations. It is only recently that we succeeded with a model able to tune the forcing by planetary waves at the tropopause level and thus reproduce such behaviour.     

高硬韧材料切削温度的解析预测

以传热学为基础，用有限差分数值方法，二元切削加工过程中切削区域温度场进行了计算机模拟，并以金刚石和硬质合金刀具切削钛合金炙例，进行了切削温度计算，经分析，计算结果与实测切削温度值吻合良好。这不但表明切削温度的计算机模拟可行的，同时人加工材料的切削加工特性提供了一种新的解析方法，可节省大量实验，为进一步预测最佳切削过程，指导新型刀具材料的开发奠定了基础。     

对偶网络拓扑法在场问题计算中的应用

网络拓扑法已被实践证明为一种有效实用的数值计算方法。它以数学分析简单、物理概念明确、单元剖分灵活、适用性强等优点,已被越来越多的场计算专家所采用,成为一种较优秀的数值分析方法。本文在普通网络拓扑法的基础上,以温度场计算为例,通过建立其能量泛函并求其极值,导出一种高精度的网络拓扑法——对偶网络拓扑法。在给定的求解精度条件下,由于两组网络计算时产生误差之间的补偿作用,使用该方法能有效地减少计算存贮空间、缩短计算用时。这对用微机求解复杂场问题是很有意义的。本文最后的实例虽然是针对温度场分析的,但对其他场问题完全适用,故具有普遍性。     

Novel Synthesis of Sol-gel Derived Nanosized Mullite Powder

Using hydrous aluminum chloride (AlCl3·6H2O) and silicon ethoxide (Si (OC2H5)4) as raw materials, a kind of nano-sized mullite powder was synthesized with the sol-gel process at the medium calcination temperature. The microstructures of the alumina-silica binary aerogel and calcined nano-sized materials were investigated by means of thermogravimetry-differential thermal analysis (TG-DTA), scanning electron microscopy (SEM) and X-ray diffractometer (XRD). The results show that the mullitization of Al2O3-SiO2 in gel starts from about 1 000 ℃ and its formation of mullite takes place in the range of 1 100 ℃-1 250 ℃. The size of the nano-sized mullite pow-der calcined at 1 250 ℃ is measured to be about 30 nm.     

蒸汽吸入对压气机气动稳定性影响试验和数值研究

研究蒸汽吸入和旋流畸变对压气机气动稳定性的影响,以某两级低速轴流压气机为试验研究对象,建立压气机蒸汽吸入和旋流畸变试验台。试验结果表明:压气机吸入蒸汽引起入口总压和总温畸变,转速增加,总压畸变强度增大,总温畸变强度减小。蒸汽吸入导致总压比和稳定裕度降低,当压气机转速为600 r/min和800 r/min时,稳定裕度分别降低15%和63%。蒸汽吸入和反向整体涡旋流畸变两者共同作用下稳定裕度下降更为显著,当转速为600 r/min和800 r/min时,稳定裕度分别降低630%和1264%。对试验压气机进行蒸汽吸入数值模拟研究,结果表明:压气机转速为600 r/min和800 r/min时,稳定裕度分别降低321%和812%。     

涡扇发动机最小红外特征模式性能寻优控制研究

为抑制涡扇发动机排气系统的红外特征,提出一种基于红外预测模型的最小红外特征模式性能寻优控制。首先,建立一种排气系统正后向红外辐射强度简化预测模型,该预测方法考虑了排气系统内高温部件和尾喷流的红外辐射,以及尾喷流对高温部件红外辐射的吸收作用,具有可信的仿真精度;其次,基于涡扇发动机部件级实时仿真模型,增加了从外涵引气冷却中心锥和尾喷管扩张段内壁的冷却结构和红外预测模块;最后,基于该模型探索了最小红外特征模式的优化原理,并选用可行序列二次规划(FSQP)算法,通过控制高温壁面冷却气的流量,主燃烧室的燃油量以及尾喷管喉道面积,对两个亚声速巡航状态的工作点进行实时优化。仿真结果表明:在满足发动机推力恒定以及其他约束条件的前提下,发动机通过最小红外特征模式性能寻优控制,其排气系统后向红外辐射下降了30%以上,红外抑制效果显著。     

基于DTW的HJ-1B卫星地表温度产品质量检验

HJ-1B卫星热红外数据应用广泛,但其地表温度反演产品的质量检验工作尚不完善。以黑河流域为研究区,利用普适性单通道算法得到HJ 1B地表温度,基于7个地面站点（下垫面为荒漠、沙漠、植被、农作物、雪地和湿地）同步观测资料和MODIS地表温度产品（MOD11A1）,引入动态时间规整方法（DTW）对站点处HJ 1B地表温度进行验证。试验结果表明：HJ 1B地表温度反演产品与地面观测值的偏差值在沙漠和荒漠站点为1K以内,均方根误差在05K左右;对于植被和农作物站点的偏差在2K以内,均方根误差为1~2K;基于DTW的验证对时序不匹配的数据评价结果与现有指标表现一致。HJ-1B地表温度反演产品与地面站点的相对偏差均低于其与MODIS地表温度反演产品的相对偏差。     

大视场红外星敏感器折反式光学系统设计

星敏感器是以恒星为探测对象的高精度空间姿态测量装置,广泛应用于卫星、航天飞机、导弹等必备的高精度姿态敏感部件。为了实现在特定环境要求下的精确应用,本文设计了可应用于近红外波长的红外光学系统。首先,根据既定的参数进行了初始结构的选型,并对马克苏托夫望远镜的形式进行了改进。然后,对设计结果进行了探测性能分析。随后对设计好的系统进行了公差分析及优化,使它能满足加工装配需求。最后,为光学系统设计了遮光罩,进行了杂散光分析。设计与分析结果表明：该探测光学系统折反射镜全表面采用球面,系统总长171.2mm,全视场14μm包围能量分布均在86%以上,0.8视场内最大畸变小于4μm。该系统视场大、结构紧凑、装调难度低、探测灵敏度高、探测范围广、温度适应性强,可在0.8～1.9μm近红外波段的宽光谱范围内进行高精度目标检测的准确检测。     

甲烷喷射温度对燃烧稳定性影响规律研究

对液氧/甲烷火箭发动机燃烧稳定性进行了数值仿真研究,比较分析了甲烷喷射温度对其燃烧稳定性的影响规律.结果表明：在222 K,224 K,226 K,228 K,230 K和234 K时,发动机燃烧稳定性较好.     

Propagation of cylindrical and spherical dust–ion acoustic solitary waves in a relativistic dusty plasma

The properties of cylindrical and spherical dust–ion acoustic solitary waves (DIASW) in an unmagnetized dusty plasma comprising of relativistic ions, Boltzmann electrons, and stationary dusty particles are investigated. Under a suitable coordinate transformation, the cylindrical KdV equation can be solved analytically. The change of the DIASW structure due to the effect of geometry, relativistic streaming factor, ion density and electron temperature is studied by numerical calculation of the cylindrical/spherical Kdv equation. It is noted that with ion pressure the effect of relativistic streaming factor to solitary waves structure is different. Without ion pressure, as the relativistic streaming factor decreases, the amplitude of the solitary wave decreases. However, when the ion pressure is taken into account, the amplitude decreases as the relativistic streaming factor increases and is highly sensitive to relativistic streaming factor. Our results may have relevance in the understanding of astrophysical plasmas.