冷轧Inconel 718合金的再结晶行为

研究了冷轧Ｉｎｃｏｎｅｌ７１８合金的再结晶行为及退火过程中硬度的变化规律。结果表明，在９１０Ｃ退火温度下，奥氏体完全再结晶，随冷轧变形量增加，完成９０％再结晶所需要的时间降低，再结晶晶粒尺寸减小。硬度的变化取决于奥氏体的回复与再结晶和б、γ″、γ′相的析出。在９１０℃退火温度下，硬度急剧降低，达到极小值后又增加，极小值点的硬度随冷轧变形量增加而增加。在８６０Ｃ退火温度下，奥氏体的回复与再结晶使冷轧变形大于２５％试样的硬度降低，随后γ″、γ′相的析出使硬度增加，达到极大值后又降低，在２ｈ后硬度缓慢增加或趋于稳定。     

高速传输图像压缩系统设计与实现

介绍一种高速传输图像压缩系统的设计和硬件实现方案。编码方法用一种改进的 SPIHT压缩编码算法 ,基于一片十万门 FPGA实现压缩核心算法的硬件。该系统目前已经实现了对帧尺寸为 1 2 8× 1 2 8,8bpp,帧频为 1 0 0 f/s的连续图像进行高速实时压缩 ,若作优化还可达到更高的帧频 ( >1 5 0 f/s)     

电动转台鲁棒控制系统设计

H∞控制理论是解决不确定性系统综合问题的有效方法。本文以ET301A型电动转台为背景, 详细讨论了H∞混合灵敏度设计中的加权函数选取问题, 给出了相应的选取原则, 并根据该选取原则进行了电动转台混合灵敏度设计, 得到满足系统鲁棒性能的控制器。系统最终调试结果满足系统的性能要求,验证了设计方法的可行性和有效性     

中国星载CCD相机控温仪性能比较

星载CCD相机热设计中的主动控温加热器一般由控温仪来完成自动控制。中国卫星普遍采用的控温仪是常规电子开关型控温仪和智能型控温仪，文章对这两种控温仪的性能进行了多个方面的比较。     

SOPC技术在软件无线电平台中的应用

介绍使用基于NIOSII软核处理器的SOPC技术,并采用基于SOPC的软件无线电技术对一个传统的抗干扰电台进行重新设计,增强了系统功能,改善了系统的灵活性,并提高了其适应不同应用需求的伸缩性。     

高强度铝合金小裂纹疲劳扩展特性

讨论面心立方多晶铝合金的表面局部塑性变形特点以及由此造成的表面小裂纹疲劳扩展特性，理论表明：当小裂纹位于试样表面时，周围环境对表层晶粒所施加的约束作用要小于对内部晶粒的约束作用。于是裂纹扩展速率会有异于线弹性断裂力学描述的规律。     

高速可编程PCM遥测帧同步器

依据国际最新测地面站的发展方向，给出了一种新型高码率可编程ＰＣＭ遥测帧同步器的方案设计，既采用了高速可编程全数字化相关检测技术及新颖的滑动窗口技术，又采用了状态机变量设计和微程序设计，并基于ＰＬＤ技术，完成了整个高速可编程ＰＣＭ遥测帧同步器的软、硬件设计、实验表明，该方案切实可行。     

沿海近地层湍流特征分析

通过对杭州湾南北两侧共四个观测点近地层湍流特征分析发现:①湍流强度随风速增大而减小。低风速时,几乎与风速呈反比,高风速时基本保持为常数。可描述为:U≤U_0时,I_k=mk/U;U>U_0时,I_k=n_K。其中n_k=a_k/ln(z/z_0),mk=a_kU_0/ln(z/z_0)。a_x=1.0,ay=0.8,a_z=0.5。海岸附近,U_0=4m/s,深入内陆1.5千米以后,U_0=3m/s。②u_*/U=k/ψ(z/L)的 Businger 模式在海岸附近与观测结果吻合很好,在内陆,-1.0≤z/L≤0.3时二者吻合较好,在此范围以外,偏离较大。③不稳定条件下,水平风速标准差可用(?)描述,垂直风速标准差可用(?)描述。稳定条件下,可用(?)(?)描述。此外,稳定条件下,有σ_w/σ_u=0.48,σ_w/σ_v=0.59;不稳定条件下有σ_w/σ_u=0.53,σ_w/σ_v=O.67。     

硬／软件综合系统可靠性研究进展

本文对计算机硬／软件综合系统的可靠性模型，以及ＦＭＥＣＡ，ＦＴＡ等故障分析技术的研究进展状况进行了一个概述。结合典型模型详细介绍了模型分类、教学处理方式和建模方法，探讨了在硬／软件综合系统可靠性建模中存在的一些特有的问题。     

Morphological and molecular changes of maize plants after seeds been flown on recoverablf satellite

Dry seeds of Zea mays, heterozygous for Lw₁/lw₁ alleles, sandwiched between nuclear track detectors aboard Chinese satellite for 15 days, were recovered and mutations in morphological characters on plants developed from these seeds, as well as their selected progenies, were investigated. The dosimetric results indicated that 85% of the seeds received at least 1 hit with Z≥20. About 10% of plants developed from flown seeds and 40% of observed selfed lines from the first generation plants showed some morphological changes, such as yellow stripes displayed on leaves, dwarf, anomogensis of floral organs and yellow-green seedlings, when compared with those from ground control. Using yellow stripes on leaves as the main endpoint for evaluating mutation induced in space environment, the frequency of stripe occurrence was 4.6% in the first generation plants, comparable with the results obtained from Long Duration Exposure Facility (LDEF) mission (Mei et al., 1994), but much lower than those from ground based ⁶⁰ Co-gamma treatment at a dose of 100 Gy, which reached 35.5% in the selfed lines of the second generation. One hundred and ten random primers were screened in RAPD analysis to detect the variation on genomic DNA of plants with stripes on leaves. Of these primers, 10.9% were able to generate polymorphic bands between mutated plants and control, also, common band patterns in several progenies with the same mutation phenotype were observed. These results demonstrated that space radiation environment could induce inheritable mutagenic effects on plant seeds, and verified the change in genetic material in the mutants. Further study will be needed for a better understand of the nature and mechanism of this induction of mutation.