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1.
《Journal of the European Ceramic Society》2022,42(13):6056-6066
We analysed with different methods the densification of UO2 nanopowders in SPS under constant heating rate (CHR) and isothermal sintering conditions. The apparent activation energy of densification in SPS (75 kJ/mol with CHR method) is significantly smaller than in conventional sintering. It is shown that this is likely not an effect of the applied current. We also observed a threshold stress at 64 MPa for the transition from pressure-insensitive sintering (stress exponent n≈0) to pressure-assisted sintering, suggesting that the contribution of the capillary stresses in such nanopowders is comparable with the typical stress applied in SPS. 相似文献
2.
CDK5 belongs to the cyclin-dependent kinase family. CDK5 is multifunctional and plays an important role in neural differentiation. However, the role of CDK5 in osteoblastic differentiation remains unclear. The present study investigated functions and molecular mechanism of CDK5 in osteoblastic differentiation. It was found that, CDK5 inhibition promoted the expression of Runx2, ALP, OCN and OPN of MSCs and the mineralization of MC-3T3E1 cells and MSCs. CDK5 inhibition enhanced the development of F-actin, nuclear localization of β-catenin and YAP, as well as the expression of RMRP RNA. When F-actin was suppressed by Blebbistatin, the nuclear localization of YAP and β-catenin, and expression of RMRP RNA as well as Runx2 and ALP were decreased. These indicate Seliciclib promotes osteoblastic differentiation mainly by F-actin. Moreover, Seliciclib also suppressed the migration of MG-63, suggesting a potential application for Seliciclib in bone defect repair and inhibition of the migration of osteosarcoma cells after osteosarcoma surgical resection. 相似文献
3.
传统的自立式铁塔通常具有足够的刚度,不需要进行非线性分析。可是,在本工程中,由于采用柔性拉杆钢管塔使用了大量的柔性拉杆,并且结构高度高具有高柔的特点,就必须采用非线性分析。本工程在进行非线性计算分析中,由于国内的计算软件已经远远不能满足要求,采用了加拿大的TOWER程序及美国MSC公司的MSC/NASTRAN软件进行计算分析比较,充分考虑了周期对结构的影响、变形对结构的影响、柔性拉杆于刚性杆件的受力差异等因素,得到真实表现结构受力的计算模型及计算方法,保证了工程的安全及顺利进行。 相似文献
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Ordered mesoporous Ni/Silica-carbon as an efficient and stable catalyst for CO2 reforming of methane
《International Journal of Hydrogen Energy》2019,44(10):4809-4820
Ordered mesoporous silica-carbon (MSC) were used as supports of Ni based catalysts for dry reforming of methane (DRM) reaction. The effects of preparation method and precipitant on the catalysts are investigated. The physical and chemical properties are discussed based on the H2-TPR, FTIR, XRD, TEM, H2-TPD and N2 adsorption/desorption characterization. It is found that the preparation method and choice of precipitants affect the catalysts significantly in terms of the properties and catalytic performance in DRM reaction. In detail, the catalysts prepared by the precipitation method show more highly dispersed Ni particles and further better catalytic activity than the impregnated catalyst. That is attributed to the forming Ni3Si2O5(OH)4 nanoflakes in the catalyst precursors with the existence of alkaline precipitants. And this Ni3Si2O5(OH)4 species bind the support more tightly than NiO in the impregnated Ni/MSC catalyst. Moreover, the choice of precipitants also influences the form of Ni3Si2O5(OH)4 species in the catalysts. Specially, the strong electrolytic capacity of NaOH gives the most Ni3Si2O5(OH)4 nanoflakes formed in Ni-MSC-1 catalyst, which results in the most highly Ni dispersity and further highest catalytic activity. Besides, the strong interaction between the Ni3Si2O5(OH)4 species and support are also advantageous to the resist sintering and formation of carbon deposition, that is related to the good catalytic stability of catalysts. 相似文献
6.
Wind turbine uses a pitch angle controller to reduce the power captured above the rated wind speed and release the mechanical stress of the drive train. This paper investigates a nonlinear PI (N-PI) based pitch angle controller, by designing an extended-order state and perturbation observer to estimate and compensate unknown time-varying nonlinearities and disturbances. The proposed N-PI does not require the accurate model and uses only one set of PI parameters to provide a global optimal performance under wind speed changes. Simulation verification is based on a simplified two-mass wind turbine model and a detailed aero-elastic wind turbine simulator (FAST), respectively. Simulation results show that the N-PI controller can provide better dynamic performances of power regulation, load stress reduction and actuator usage, comparing with the conventional PI and gain-scheduled PI controller, and better robustness against of model uncertainties than feedback linearization control. 相似文献
7.
利用模块化设计思想,在Matlab编程环境下实现了基于多条耦合器双声路声表面波器件的设计仿真平台。为了提高MSC双声路SAW器件的性能,该平台将多条耦合器、分裂指及假指设计方案融合到器件设计中。多条耦合器不仅实现了两个变迹换能器传递函数的乘积,而且消除了体声波对器件性能的影响。假指消除了通过变迹换能器引起的波前畸变。分裂指可以最小化换能器内部的声波反射问题。通过一个频率为203.559MHz的基于多条耦合器双声路声表面波器件的设计和实际测试结果的对比分析,证明了该设计仿真平台不仅可以进行器件版图结构的设计和模拟,而且设计平台所得到的版图和数据可以用于器件的掩膜版制作和器件封装尺寸参考。另外,该仿真设计平台可以很好地实现对器件的脉冲特性、频率响应特性的模拟和仿真。 相似文献
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9.
应用分析软件MSC.Nastran,对单段锤式破碎机主轴结构进行了有限元静强度分析。对原结构进行了优化改进,由原方形形式改为圆形形式。研究结果表明:改进后的主轴具有足够的强度及刚度,同时也简化了加工工艺,为结构优化设计提供理论依据。 相似文献
10.
软交换系统"大容量、少局所"的建设方式,容灾备份技木在移动软交换网络中变得尤为关键,相对传统的"1+1"、"N+1"备份方式,MSC Pool技术具有多方面的优势,文章结合工程实际情况提出软交换系统MSC Pool改造方案,为同类工程的建设提供理论和技术指导。 相似文献