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利用松散耦合方法建立离心式压气机稳态流-热-固耦合模型,将离心式压气机解耦成气动、传热和结构三个子系统,子系统间存在热、力和变形的传递。由于不匹配的网格划分,利用反距离平均方法构造插值函数实现热与力向结构的传递,采用统一有限元模型实现热-固顺序耦合分析,利用网格重生成技术实现结构变形到气动分析模型的传递。经过3次迭代离心式压气机耦合系统达到收敛。结果表明,分析的离心式压气机内部流-热-固耦合强烈,耦合解法与非耦合解法得到压气机响应存在较大差异,对于多学科耦合强烈的构件,需要考虑学科间的耦合效应反应真实的工作状况。 相似文献
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为了构建稳定过表达Runx2 (骨特异性转录因子)的C2C12 (小鼠成肌细胞)和MG63 (前成骨细胞)细胞株, 并用于研究Runx2在对抗空间骨丢失效应中的作用. 利用实时定量聚合酶链式反应鉴定Runx2下游基因I型胶原、碱性磷酸酶表达情况, 在二维回转器中培养稳定细胞株, 通过定量聚合酶链式反应,观察在模拟失重效应下Runx2基因对其下游基因表达的影响. 结果表明, 通过筛选获得稳定转染的C2C12-Runx2和MG63-Runx2细胞株, 经鉴定都能过表达Runx2. 转染后的细胞 I 型胶原和碱性磷酸酶mRNA表达增高. 回转组与对照组相比, MG63, C2C12-Runx2, MG63-Runx2细胞的I型胶原和碱性磷酸酶mRNA表达降低, 但在模拟失重效应下, 转染细胞中I型胶原和碱性磷酸酶的mRNA表达下降程度明显低于未转染细胞株. 所构建的C2C12-Runx2和MG63-Runx2细胞株比较稳定, 并证实Runx2能部分对抗失重引起的成骨特异性分子的降低. 相似文献
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航天员在长期失重环境影响下,会容易造成椎体失重性骨质疏松。为了探究骨质流失对腰椎承载能力的影响,设计了不同骨密度的腰椎力学仿真,通过图像处理建立了腰椎三维模型,利用有限元算法得到腰椎应力分布,对比了不同材料属性腰椎模型应力结果。结果表明:骨质疏松腰椎的应力值较正常腰椎变小,而形变量却明显增大。可以看出,骨质流失时,会导致腰椎骨骼材料性能发生变化,使腰椎形变量增大,并且使腰椎结构承载能力降低。 相似文献
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M. Nelson W.F. DempsterJ.P. Allen 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(5):675-683
Development of reliable and robust strategies for long-term life support for planetary exploration must be built from real-time experimentation to verify and improve system components. Also critical is incorporating a range of viable options to handle potential short-term life system imbalances. This paper revisits some of the conceptual framework for a Mars base prototype which has been developed by the authors along with others previously advanced (“Mars on Earth®”) in the light of three years of experimentation in the Laboratory Biosphere, further investigation of system alternatives and the advent of other innovative engineering and agri-ecosystem approaches. Several experiments with candidate space agriculture crops have demonstrated the higher productivity possible with elevated light levels and improved environmental controls. For example, crops of sweet potatoes exceeded original Mars base prototype projections by an average of 46% (53% for best crop) ultradwarf (Apogee) wheat by 9% (23% for best crop), pinto bean by 13% (31% for best crop). These production levels, although they may be increased with further optimization of lighting regimes, environmental parameters, crop density etc. offer evidence that a soil-based system can be as productive as the hydroponic systems which have dominated space life support scenarios and research. But soil also offers distinct advantages: the capability to be created on the Moon or Mars using in situ space resources, reduces long-term reliance on consumables and imported resources, and more readily recycling and incorporating crew and crop waste products. In addition, a living soil contains a complex microbial ecosystem which helps prevent the buildup of trace gases or compounds, and thus assist with air and water purification. The atmospheric dynamics of these crops were studied in the Laboratory Biosphere adding to the database necessary for managing the mixed stands of crops essential for supplying a nutritionally adequate diet in space. This paper explores some of the challenges of small bioregenerative life support: air-sealing and facility architecture/design, balance of short-term variations of carbon dioxide and oxygen through staggered plantings, options for additional atmospheric buffers and sinks, lighting/energy efficiency engineering, crop and waste product recycling approaches, and human factor considerations in the design and operation of a Mars base. An “Earth to Mars” project, forging the ability to live sustainably in space (as on Earth) requires continued research and testing of these components and integrated subsystems; and developing a step-by-step learning process. 相似文献
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叶轮叶片是复杂的空间曲面体,它直接影响到水泵的水力性能及运行稳定性.发动机水泵叶轮流动叠加设计是通过分析流体的流动规律,按其流动轨迹进行叶轮设计,将流体在离心水泵内的流动看作叶轮静止时的轴向和径向流动和叶轮旋转时的周向流动的叠加,从而用绕角流动和源环流的流体流动规律设计出叶轮的轴面轮廓和叶片骨线.通过CFD(Computational Fluid Dynamics)仿真,可以证明该方法从结构上避免了流体流动过程中由于空间的相对不均而造成的压力不均,减轻了回流、二次流,相应地减少能量的损失,提高水泵的效率. 相似文献
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为了研究颞骨蜂房气化程度与血管性耳鸣之间的生物力学关系,本文基于典型的血管性耳鸣患者的数据进行了计算分析。首先,基于血管性耳鸣患者CT图像分别建立颞骨蜂房的基础气化和过度气化2种气化程度的三维几何模型。然后,将三维几何模型分别导入Hypermesh软件中并以四面体单元进行网格划分,生成可计算的三维有限元(FE)模型。再将三维有限元模型导入Virtual.Lab Acoustics软件中,加载相同速度边界条件,计算模型的声压幅值响应。最后,以前庭处检测的声压幅值作为计算结果。由2个模型生物力学数值模拟计算的结果,可以发现频率为250 Hz时经气化模型产生的声压幅值比基础模型的值低3.02 dB。经过气化模型产生的声压幅值小于基础模型,且在相同频率下2个模型间的声压幅值差异可被血管性耳鸣患者察觉。这一结论可以尝试为临床创新治疗血管性耳鸣提供新的理论依据。 相似文献
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