天问一号火星探测器产品保证工作实践

分析了火星探测器任务环境复杂、软件自主性高、验证任务重、材料选用控制难等特点,总结了天问一号火星探测器在狠抓风险识别与管控、聚焦软件系统设计源头,严格试验考核,以及严控材料选用及验证等方面采取的主要产品保证工作措施.上述措施有效保证了天问一号火星探测器的产品质量,可为后续火星探测器及其他行星际探测器研制过程的产品保证工作提供借鉴.     

机翼结构布局优化的并行子空间方法

机翼内部构件的布局优劣在很大程度上影响着机翼结构质量,因此进行布局优化设计尤为重要。采用并行子空间方法求解机翼结构布局优化的问题,将机翼结构布局设计问题分为梁站位优化、桁条优化和厚度优化三个并行的子空间,设计变量在各自的子空间内单独优化;各子空间优化结束后,在系统级中协调三个子空间的设计变量,保持最小质量的子空间的优化变量不变;采用近似一维搜索的方法协调其他子空间的设计变量,然后进行变量迭代直至收敛。结果表明:该方法具有较高的优化效率,能够取得较好的优化结果,具有实际工程应用价值。     

先进的宇航试验舱温控系统

介绍了中国新一代宇航试验舱的温控系统。该温控系统设计思想先进、结构新颖。在直径２．３ｍ,长２ｍ的封闭舱体控温面上,实现了０℃～５０℃的任意温度定点控制及９０ｍｉｎ内的正弦波、梯形波、三角波的周期变化;在整个控温面上温度非均匀性（均方根偏差）小于０．３℃,远远超过了非均匀度±１℃、控制精度±２℃的原设计指标。     

APPLICATION OF HOT PRESS SINTERING TECHNIQUE TO EXPLOSIVE CHARGE LINER OF PETROLEUM PERFORATION BULLET

介绍了一种制备石油射孔弹的药形罩的新方法,采用粉末冶金技术,热压烧结工艺制备石油射孔弹的药形罩,并对药形罩的烧结工艺进行了研究。实验结果表明,采用该工艺制备的石油射孔弹药形罩可以满足要求。     

GRACE gravity field modeling with an investigation on correlation between nuisance parameters and gravity field coefficients

The GRACE (Gravity Recovery And Climate Experiment) monthly gravity models have been independently produced and published by several research institutions, such as Center for Space Research (CSR), GeoForschungsZentrum (GFZ), Jet Propulsion Laboratory (JPL), Centre National d’Etudes Spatiales (CNES) and Delft Institute of Earth Observation and Space Systems (DEOS). According to their processing standards, above institutions use the traditional variational approach except that the DEOS exploits the acceleration approach. The background force models employed are rather similar. The produced gravity field models generally agree with one another in the spatial pattern. However, there are some discrepancies in the gravity signal amplitude between solutions produced by different institutions. In particular, 10%–30% signal amplitude differences in some river basins can be observed. In this paper, we implemented a variant of the traditional variational approach and computed two sets of monthly gravity field solutions using the data from January 2005 to December 2006. The input data are K-band range-rates (KBRR) and kinematic orbits of GRACE satellites. The main difference in the production of our two types of models is how to deal with nuisance parameters. This type of parameters is necessary to absorb low-frequency errors in the data, which are mainly the aliasing and instrument errors. One way is to remove the nuisance parameters before estimating the geopotential coefficients, called NPARB approach in the paper. The other way is to estimate the nuisance parameters and geopotential coefficients simultaneously, called NPESS approach. These two types of solutions mainly differ in geopotential coefficients from degree 2 to 5. This can be explained by the fact that the nuisance parameters and the gravity field coefficients are highly correlated, particularly at low degrees. We compare these solutions with the official and published ones by means of spectral analysis. It is found that our solutions are, in general, consistent with others in the spatial pattern. The water storage variations of the Amazon, Chari and Ganges river basins have also been computed. The variations computed with the NPARB approach are closer to those produced by JPL and DEOS solutions, while the variations produced with the NPESS approach are in good agreement with those produced by the CSR and GFZ solutions. A simulation study is implemented with considering realistic noise and low-frequency error. The two approaches are used to recover the true model. The NPESS solution appears closer to the true one. Therefore we are inclined to estimate the nuisance parameters simultaneously with the geopential coefficients.     

Parylene真空涂覆新工艺研究

简述了Parylene真空沉积的机理,并对采用Parylene真空涂覆的涂层样件进行了全面的性能摸底试验。     

梯度热障涂层的设计

 采用电子束物理气相沉积方法 (EB PVD)制备了梯度热障涂层,其结构设计为NiCoCrAlY粘结层 /Al₂O₃ YSZ过渡层 /YSZ陶瓷层。YSZ陶瓷层的结构为柱状晶结构,Al₂O₃ YSZ梯度过渡层为梯度微孔结构。采用有限元方法对梯度热障涂层进行热应力分析,优化了Al₂O₃ YSZ梯度过渡层的组成。计算结果表明,梯度涂层的内应力显著降低,而且界面及其附近应力和应变变化较平缓。过渡层厚度的增加有利于降低涂层内应力和缓和涂层界面处的应力集中。     

地坪的热膨胀在飞机制造中对互换协调的影响

本文针对大、中型飞机生产中出现的严重不协调现象,对厂房地坪相对于室温变化的伸缩情况,进行了试验研究。测出了厂房地坪相对于室温变化的伪热膨胀系数α地伪,找出了在与地坪固定的型架中装配产品时,产生严重不协调现象的原因是厂房地坪的伪热膨胀系数大大小于工装和产品常用材料钢和铝合金的热膨胀系数,而严重地影响着固定于地坪上的型架中各尺寸随室温变化的伸缩量。同时也导出了在不同结构型式、不同材料的工装间,在不同室温下装配产品时,所产生的热膨胀综合误差的通用计算公式。探讨了型架结构发展的方向。     

涡轮叶片气膜冷却的研究

本文针对涡轮叶片离散气膜孔结构及叶片表面具有不同曲率的特点 ,采用传质比拟、数值计算及可视化技术 ,通过比较平板、弯曲壁面及涡轮叶片的气膜冷却流动及传热特性 ,系统地研究了离散孔三维效应、壁面曲率及压力梯度诸因素对叶片气膜冷却的影响。在此基础上 ,提出了估算叶片头部、中弧区及尾缘气膜冷却有效温比的准则公式、实验曲线及计算机程序     

劈绕射系数的一种通用表达式及应用

 在讨论矩形波导辐射场、飞行器翼边电磁散射场时,要用到二维金属尖劈的绕射系数表达式。许多学者对尖劈绕射场进行了详细讨论,给出了明确结果,其中级数形式的严格解收敛速度较慢,简化公式是当源置于无限远处取得的,对于尖劈近区场源问题没有触及,文献[2]给出的简化解析式在应用上有一定的困难。因此我们重新进行了推导,获得一种新的表达式,适合于近、远场源问题的数值计算。矩形波导棱边的绕射是普通劈尖的一个特例。