Soybean cultivation for Bioregenerative Life Support Systems (BLSSs): The effect of hydroponic system and nitrogen source

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.     

Predictive Space Weather: An information theory approach

It is rather well recognized that the global dynamics of the Sun–Earth relationship involves complex nonlinear phenomena. Here we present a preliminary attempt to characterize the influence and the timing of the solar magnetic activity on the near-Earth environment, based on quite novel tools based on concepts from information theory.     

Start-up current adaptive control for sensorless high-speed brushless DC motors based on inverse system method and internal mode controller

The start-up current control of the high-speed brushless DC (HS-BLDC) motor is a chal-lenging research topic. To effectively control the start-up current of the sensorless HS-BLDC motor, an adaptive control method is proposed based on the adaptive neural network (ANN) inverse system and the two degrees of freedom (2-DOF) internal model controller (IMC). The HS-BLDC motor is identified by the online least squares support vector machine (OLS-SVM) algo-rithm to regulate the ANN inverse controller parameters in real time. A pseudo linear system is developed by introducing the constructed real-time inverse system into the original HS-BLDC motor system. Based on the characteristics of the pseudo linear system, an extra closed-loop feed-back control strategy based on the 2-DOF IMC is proposed to improve the transient response per-formance and enhance the stability of the control system. The simulation and experimental results show that the proposed control method is effective and perfect start-up current tracking perfor-mance is achieved.     

服务型制造模式下民机企业价值网络研究

基于航空制造行业背景,对服务型制造模式下民机企业价值网络展开探讨。首先分析服务型制造模式的价值源泉,重点讨论其价值共创机制,引出了价值共创的条件——价值网络;其次,分析服务型制造企业由价值链向价值网络管理的转变过程,提出服务型制造价值网络概念,并总结出服务型制造企业的价值网络特性及本质;最后,以航空制造业为例,分析其价...     

单轴拉伸和压缩镁合金各滑移系的Schmid因子计算

针对单轴拉伸和压缩条件下的镁合金,计算了不同滑移系（基面滑移、柱面滑移、锥面滑移、锥面滑移）在整个取向空间中的Schmid因子分布.计算结果表明,基面滑移、柱面滑移和锥面滑移系的Schmid因子在取向空间中都有0.5的极大值;而锥面滑移系的Schmid因子普遍较低,当θ在80°左右,ψ在70°左右时的最大值仅为0.383.计算结果为镁合金变形机制的分析提供基础.     

New concepts for the avoidance or utilisation of methane in life support systems

Due to high resupply costs, especially for long-duration stays in space habitats beyond low earth orbit, future manned space missions will require life support systems (LSS) with a high degree of regenerativity. Possible ways to overcome the waste of resources and to save on resupply mass are therefore of major interest for the development of next generation environmental control and life support systems.     

风驱雨CFD模拟及平均雨荷载计算方法研究

基于谐波叠加法,用Kaimal谱生成空旷场地的脉动风速时程,将脉动风速时程作为流场CFD模拟的速度入口。采用分离涡模型模拟脉动风场并用离散相模拟雨滴颗粒,通过风雨耦合的CFD模型,获得雨滴落在输电塔各高度处的雨滴速度以及时间,并依据冲量定理和冲量等效原则,提出了任一时距的平均雨荷载计算方法。以176m高的输电塔为例,计算出作用在输电塔上以0.25s为时距的平均雨荷载。研究了水平风速和降雨强度对平均雨荷载的影响,结果显示:水平平均雨荷载随水平风速和降雨强度的增加而增加,但水平平均雨荷载与风荷载的比值沿高度增加而递减;尽管单粒雨滴荷载较大,但作用时间只有大约1×10-5s,依据冲量等效原则计算得出在一定时距内的平均雨荷载较小;对于本文算例,平均雨荷载与平均风荷载的比值不超过2.6%。     

多渐消因子Kalman滤波器在SINS初始对准中的应用(英文)

针对系统模型和统计信息不能精确已知的条件下Kalman滤波无法给出最优解这一问题,单一渐消因子Kalman滤波算法对于简单的系统是有效的,但是对于复杂的多变量系统,仅仅利用单个的渐消因子是不够的。本文提出了一种多渐消因子滤波算法,通过利用开窗法计算新息序列协方差的无偏估计获得渐消因子矩阵。利用渐消因子矩阵调节一步预测均方误差矩阵k|k1P,对不同的滤波通道提供不同的渐消速率。将该方法应用于SINS的初始对准中,仿真和试验结果表明:当真实系统噪声统计特性同设定参数不一致时,对准精度明显高于其他滤波算法。其对不确定性噪声具有较低的敏感度,对系统参数具有较好的滤波效果。因而,在实际应用中具有重要的参考价值。