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《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2020,65(8):1894-1909
In this work Photosynthetically Active Radiation (PAR) in oceanic and mediterranean climates is modeled. Twenty-two different models have been developed and tested: eleven Multilinear Regression (MR) models and eleven Artificial Neuron Network (ANN) models, using combinations of variables such as Global Horizontal Irradiance (GHI), Global Extraterrestrial Irradiance (G0), Temperature (T) and Relative Humidity (RH). Data provided by Satellite Application Facility on Climate Monitoring (CM SAF) are used to develop and train the models, while the models have been validated using field data from four stations located in Spain, covering the different study climates.According to the results, zones with different climate conditions need different models, both for the case of MR and ANN. The results show the need of including the GHI in all models in order to obtain accurate estimates; in fact, the presence of more variables only improves slightly the results in mediterranean climate, while in oceanic climate no improvement is observed.On the other hand, comparing MR and ANN models, ANN models did not show better results than those of MR models in no one of the cases studied. Regarding the climate, both types of models are clearly better for the mediterranean case than for the oceanic one. In order to improve the performance of the model for oceanic climate a correction based on the site adaptation technique was carried out. The good results obtained by this technique fully justify its use.The best proposed models provide better performance than other models which are restricted to certain locations. Besides, the clustering technique based on the PAR variable, used in this work, allows obtaining useful models for a whole region. Finally, another advantage of this methodology is that there is no need of ground measurements for its development, except for the site adaptation technique. 相似文献
964.
有源集成背馈式接收天线设计 总被引:1,自引:0,他引:1
为了提高接收天线系统的增益以及灵敏度,对于天线与射频前端组成的接收系统采用了一种有源集成接收天线的设计方案,从而省略了传统设计中的有源电路与微带天线之间的匹配网络.依照此方案,设计并实现了一个背馈结构的矩形微带天线与前级低噪声放大器电路的有源集成.矩形微带天线的馈电点与低噪声放大器的输入端通过金属探针相连,当天线在2.48?GHz谐振时,通过选择合适的馈电点位置,天线产生放大器设计所需的输入阻抗.有源集成背馈式接收天线工作于S波段,最终的测试结果显示了其优良的特性. 相似文献
965.
Roberta Paradiso Roberta Buonomo Mike A. Dixon Giancarlo Barbieri Stefania De Pascale 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
Soybean [Glycine max (L.) Merr.] is one of the plant species selected within the European Space Agency (ESA) Micro-Ecological Life Support System Alternative (MELiSSA) project for hydroponic cultivation in Biological Life Support Systems (BLSSs), because of the high nutritional value of seeds. Root symbiosis of soybean with Bradirhizobium japonicum contributes to plant nutrition in soil, providing ammonium through the bacterial fixation of atmospheric nitrogen. The aim of this study was to evaluate the effects of two hydroponic systems, Nutrient Film Technique (NFT) and cultivation on rockwool, and two nitrogen sources in the nutrient solution, nitrate (as Ca(NO3)2 and KNO3) and urea (CO(NH2)2), on root symbiosis, plant growth and seeds production of soybean. Plants of cultivar ‘OT8914’, inoculated with B. japonicum strain BUS-2, were grown in a growth chamber, under controlled environmental conditions. 相似文献
966.
Piero Spillantini 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2012
The equilibrium temperature of a system in space can be lowered by a suitable choice of its geometry and its attitude. This remark is important for devices based on medium temperature and high temperature superconducting materials, and offers the possibility of their fully passive cooling without or with a marginal recourse to active systems. General parameterizations are given and simple schemes discussed. The adopted geometrical configuration and the attitude can enhance the role of passive cooling of the large superconducting magnetic systems required for protecting from ionizing radiation manned habitats in deep space. A specific example based on MgB2 cable for protecting large volume habitats (500 and 1000 m3) is treated. The systems can be run in deep space at equilibrium temperatures around 20 K mainly by passive cooling, provided that their geometry and attitude would be suitably chosen. 相似文献
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旋转状态气膜换热机理的数值研究 总被引:1,自引:1,他引:0
大涡模拟研究了旋转对单孔平板气膜冷却的影响,气膜出流的雷诺数为2600,吹风比为0.5,计算了静止和旋转数为0.02两种状态的流动和换热,从湍流结构演化的角度讨论了旋转状态气膜换热的机理.结果表明:①发卡涡是决定气膜换热的主要湍流结构,旋转状态发卡涡的形状和运动规律主要受哥氏力的影响;②气膜在哥氏力作用下向高半径方向偏... 相似文献