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T W Tibbitts W Cao 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(11):427-433
This report discusses the advantages and limitations of several different procedures for growth of potatoes for CELSS. Solution culture, in which roots and stolons are submerged, and aeroponic culture were not found useful for potatoes because stolons did not produce tubers unless a severe stress was applied to the plants. In detailed comparison studies, three selected culture systems were compared, nutrient film technique (NFT), NFT with shallow media, and pot culture with deep media. For the NFT and NFT plus shallow media, plants were grown in 0.3 m2 trays and for the deep medium culture, in 20 liter pots. A 1 cm depth of arcillite, a baked montmorillonite clay, was used as shallow media (NFT-arc). Peat-vermiculite mixture was used to fill the pots for the deep media. Nutrient solution, modified half-strength Hoagland's, was recirculated among the tray culture plants with pH automatically controlled at 5.5, and conductivity maintained at approximately 1100 microS cm-1 by adding stock nutrients or renewing the solution. A separate nutrient solution was used to water the pot plants four times daily to excess and the excess was discarded. Plants of Norland cv. were utilized and transplanted from sterile-propagated stem cutting plantlets. The plants were grown for 66 days under 12 h photoperiod in a first study and grown for 54 days under 24 h photoperiod in a second study. Under both photoperiods, total plant growth was greater in NFT-arc than in either NFT or pot culture. Under 12 h photoperiod, tuber dry weight was 30% higher with NFT-arc, but 50% lower with NFT, than with pot culture. Under 24 h photoperiod, however, tuber dry weight in both NFT and NFT-arc was only 20% of that in pot culture. The NFT and NFT-arc produced a greater shoot growth and larger number of small tubers than pot culture, especially with 24 h photoperiod. It is concluded that there are serious limitations to the use of NFT alone for growth of potatoes in a CELSS system. These limitations can be minimized by using a modified NFT with a shallow layer of media, such as arcillite, yet additional work is needed to ensure high tuber production with this system under long photoperiods. 相似文献
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A method of motion compensation for inverse synthetic aperture radar (ISAR) is proposed. The techniques of interpolation, cross correlation, and estimation are used together. Essential to the method is the fact that avoiding cross-range image aliasing due to Doppler ambiguities requires range profiles to be generated at an adequate rate. The effect of noise on motion compensation is studied by means of simulation. The quality of the reconstructed image is used to evaluate the method 相似文献
686.
有热解的轴对称烧蚀体传热有限元计算 总被引:1,自引:0,他引:1
本文采用有限元法,分析和计算了有热解的再入烧蚀体的传热问题。计算方法和程序先用两个算例进行了考证,最后给出了沿真实弹道的计算结果。 相似文献
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曹翠微%肖琰%魏伯荣 《宇航材料工艺》2006,36(4):58-60
介绍了用动态热机械分析仪测定天然橡胶(NR)硫化胶耐老化性能的原理及方法。通过测定胶料在160℃、恒温30min下的动态模量谱,来评估硫化胶的耐老化性能。同时测定硫化胶力学性能随老化时间的变化情况。结果显示:老化后储能模量减少,损耗模量和损耗因子tanδ总体呈增加趋势。力学性能随老化时间的延长呈先增加而后下降趋势。 相似文献
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描述了一台能够对长度达1m的线纹尺和长度达2m的光栅尺(线位移传感器)进行测量的激光干涉仪,干涉仪设计成了双干涉光路系统,以消除光栅尺安装引入的阿贝误差,这台测量仪采用干涉条纹计量原理,对光栅尺和线纹尺的线值精度进行检测,并能对光机信号的质量进行评价。测量过程中,对空气折射率实现了实时修正。 相似文献
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研究JPEG2000标准中CDF9/7提升小波的硬件实现问题,提出一种适合大尺寸卫星图像实时处理的FP GA设计,并对其进行仿真验证。该设计使用VHDL语言进行描述,并以XiLinxVirtexII系列中的xc2v1000-4bg575器件 为基础,在ise6.1下完成综合,用Modelsim5.8进行后仿真。综合器件最高工作时钟110MHz。分析表明,该设计在功耗 和资源敏感的场合具有优势。 相似文献
690.
铝粉颗粒燃烧及其燃烧产物凝聚成核计算研究 总被引:3,自引:2,他引:3
在建立铝颗粒燃烧模型及其燃烧产物凝聚成核模型基础上,对铝粉燃烧所形成的Al2O3平均粒径了进行了计算研究。也对推进剂燃烧环境下铝颗粒燃烧区域中温度、燃烧产物的质量分数、过饱和度及其凝聚成核速度的变化规律进行了分析讨论。 相似文献