650 mm口径主反射镜组件结构设计

为提高遥感相机主反射镜的在轨面形和结构稳定度,文章对φ650 mm主反射镜组件进行了特殊结构设计,采用传统的装框式支撑结构,通过设计使胶斑切向受力,以有效解决镜子和支撑结构材料热失调问题。力学和热特性计算表明:主反射镜面形在y向(地面装调方向)1g重力作用下的峰谷值(PV)变化为2.30 nm,均方根值(RMS)变化为0.42 nm,镜子顶点位置变化为0.8μm,光轴变化为0.01″;在相机温控指标(20±2)℃环境下,反射镜的PV变化为3.02 nm,RMS变化为0.56 nm;主反射镜的计算仿真基频为164.3 Hz。主反射镜组件振动试验结果显示组件的实际基频为158.0 Hz,与仿真计算结果基本一致。经过振动和真空放气试验,组件的结构接口稳定性均为平移不大于3μm,角度变化不大于3″。以上全部满足设计指标要求。     

Physiologic and metabolic responses of wheat seedlings to elevated and super-elevated carbon dioxide

The metabolic consequence of suboptimal (400 μmol mol⁻¹ or ppm), near-optimal (1500 ppm) and supra-optimal (10,000 ppm) atmospheric carbon dioxide concentrations [CO₂] was investigated in an attempt to reveal plausible underlying mechanisms for the differential physiological and developmental responses to increasing [CO₂]. Both non-targeted and targeted metabolite profiling by GC–MS and LC–MS were employed to examine primary and secondary metabolites in wheat (Triticum aestivum, cv Yocoro rojo) continuously exposed to these [CO₂] levels for 14, 21 and 28 days. Metabolite profile was altered by both [CO₂] and physiological age. In general, plants grown under high [CO₂] exhibited a metabolite profile characteristic of older plants under ambient CO₂. Elevated [CO₂] resulted in higher levels of phosphorylated sugar intermediates, though no clear trend in the content of reducing sugars was observed. Transient starch content was enhanced by increasing [CO₂] to a much greater extent at 10,000 ppm CO₂ than at 1500 ppm CO₂. The percentage increase of starch content resulting from CO₂ enrichment declined as plants develope. In contrast, elevated [CO₂] promoted the accumulation of secondary metabolites (flavonoids) progressively to a greater extent as plants became mature. Elevated [CO₂] to 1500 ppm induced a higher initial growth rate, while super-elevated [CO₂] appeared to negate such initial growth promotion. However, after 4 weeks, there was no difference in vegetative growth between 1500 and 10,000 ppm CO₂-grown plants, both elevated CO₂ levels resulted in an overall 25% increase in biomass over the control plants. More interestingly, elevated atmospheric [CO₂] reduced evapotranspiration rate (ET), but further increase to the supra-optimal level resulted in increased ET (a reversed trend), i.e. ET at 1500 ppm < ET at 10,000 ppm < ET at 400 ppm. The differential effect of elevated and super-elevated CO₂ on plants was further reflected in the nitrogen dynamics. These results provide the potential metabolic basis for the differential productivity and stomatal function of plants grown under elevated and super-elevated CO₂ levels.     

针对电视／红外导引头的镜面干扰法

随着“空地一体化”和“数字化”作战理论在战争中的应用，以电视／红外制导武器为主的防区外精确打击能力，成为空军现代化水平的主要标志之一。在介绍电视／红外制导空地导弹武器系统末制导段的工作过程和图像跟踪原理的基础上，对电视／红外导引头的特点及其跟踪过程进行了深入分析，得出电视／红外导引头光电干扰的实现方法。针对现有干扰方法的缺点，提出了一种新的光电干扰方法——镜面干扰方法。     

Secondary instability of separated shear layers

The process through which a laminar flow undergoes transition to turbulence is of great fundamental and practical interest. Such a process is hugely complex as there are many diverse routes for a laminar flow to become turbulent flow. The transition process is usually initiated by flow instabilities—a primary instability stage followed by a secondary instability stage. This forms a rational framework for the early stage of a transition process and it is crucially important to understand the physics of instabilities leading to turbulence. This article reviews the results of studies on secondary instability of separated shear layers in separation bubbles and summaries the current status of our understanding in this area.     

LaBr3(Ce)元件破损在线监测关键核素确定及效率校准

常用的元件破损在线监测方法受外在因素影响较大，以γ能谱中关键裂变产物核素比活度进行在线定量分析是一种可靠的元件破损监测方法。针对新型LaBr₃(Ce)元件破损监测仪，设计了元件破损模拟实验，对逸出的裂变产物采用HPGe和LaBr₃(Ce)探测器进行了对比测量。通过不同冷却时间γ能谱的核素分析，确定了¹³⁵Xe，⁸⁸Kr，¹³⁸Xe，⁸⁸Rb，¹³⁸Cs等可作为LaBr₃(Ce)元件破损γ能谱监测的关键核素。同时，制备了覆盖能量范围(250～2 400)keV，含⁶⁰Co，¹³⁷Cs，¹³³Ba；²⁴¹Am，¹⁵²Eu；¹⁰⁹Cd，⁸⁸Y，⁵⁷Co及²⁴Na的4组放射性标准溶液，在建立的效率校准系统上，校准了LaBr₃(Ce)在线监测仪的效率。在反应堆一次异常情况分析中，已校准的LaBr₃(Ce)元件破损监测仪对关键核素的现场分析结果与HPGe的取样分析结果一致，表明效率校准结果准确，校准方法可靠。     

建立室内虚拟长度基线场的可行性探讨

提出了利用两平面反射镜多次反射来虚拟室外基线场,在室内完成检定光电测距仪及全站型电子速测仪测距部分的解决方案;在现有技术的层面上对该方案所面临的技术难题进行了探讨,对其可行性进行了论证;对该方案实施1000 m测长的不确定度进行了详细的分析和计算,得出了该方案完全可行的结论.     

新型反射镜材料——碳化硅

对几种常用反射镜材料的物理性能和工艺性能进行了比较，研究了碳化硅轻质反射镜的制作工艺，结果认为：反应烧结是实现这种材料作为反射镜材料的巨大潜力的最有效的工艺，可以实现形状复杂产品的近净尺寸成型，样品在烧结过程中无收缩；样品处理时间短；无需特殊设备，在烧结过程中无需加压，样品尺寸原则上仅受烧结炉大小的限制,帛品近乎安全致密。这项研究的突破，主要依赖于反射镜成型方法及反射镜面光学加工的研究进展。最后简述了美国和俄罗斯在这方面的研究进展。     

空间遥感器大口径轻量化扫描镜材料发展与制作方法探讨

扫描镜是光机扫描型空间遥感器的重要组成元件。文章针对目前空间遥感器上应用的大口径轻量化扫描镜,从材料和制作方法方面进行了一定的技术研究。     

大型太阳模拟器拼接准直镜技术

KM6太阳模拟器采用离轴准直光学系统,离轴角为29°,准直角≤±2°,准直镜最大外形直径为6800mm。根据太阳模拟器光学系统的特性,同时也为降低制造成本,准直镜可以采用球面反射镜来代替原本的抛物面反射镜,并且采用多个小镜拼接而成。文章从外形尺寸计算、单元准直镜及其调节机构、框架结构及其调节机构、准直镜的温控和准直镜的装调等方面全面介绍了KM6太阳模拟器拼接准直镜的设计技术。与此同时,详细阐述了在平面结构基础上拼接大型球面反射镜的可行性及其相关位置尺寸的计算方法,阐述了单元准直镜和框架的调节机构的原理及其拼接球面反射镜过程中的作用,论述了准直镜辐射制冷、电加热调温的温控方案的可行性,进行了必要的热分析计算,对空间环境模拟器中大型反射镜的研制具有参考价值。     

KM6太阳模拟器拼接式准直镜的装校技术

KM6太阳模拟器准直镜是由121块正六边形的球面单元镜拼接而成,拼接后有效口径为6636mm、曲率半径为24800mm。文章分析了3种经典的球面反射镜光学装校的原理,并根据KM6太阳模拟器光学系统的结构参数,确定用平行激光束聚焦的原理装校准直镜。以该原理为基础设计了360°旋转式装校装置,结构简单易行,很好地实现了准直镜的光学装校。文章还分析了装校过程中测量仪器误差、操作人员判读误差对准直镜装校精度的影响。