共查询到17条相似文献,搜索用时 109 毫秒
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分析丝杠的简化圆柱杠精确求解的现状后,运用泛灰色不确定性系统理论,建立了丝杠的简化圆柱杠求解不确定性系统模型USM-1,给出了精度检验方法。编制了MATLAB程序,给出了了计算实例,并与回归模型进行了比较。该模型不仅适合于等间距建模,也适合于非等间距建模,具有精度高、使用简便等特点,值得在数控机床设计中推广使用。 相似文献
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目的: 考察硫酸化茯苓多糖(SP)对1-甲基-4-苯基-1,2,3,6-四氢吡啶(MPTP)诱导的帕金森小鼠脑组织抗氧化能力的影响。方法: MPTP注射ICR小鼠制备帕金森病(PD)模型。将ICR小鼠随机分为5组:对照组、MPTP组和SP治疗组(50,100,150 mg/kg),腹腔注射给药。紫外分光光度法检测小鼠纹状体中超氧化物岐化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)、过氧化氢酶(CAT)、乳酸脱氢酶(LDH)的活性和抗超氧阴离子活力以及过氧化氢(H2O2)、丙二醛(MDA)的含量,HE染色观察小鼠脑组织形态学变化。结果: 与模型组相比,在一定浓度范围内,SP治疗组小鼠纹状体GSH-Px、SOD、CAT、LDH活性及抗超氧阴离子活力有不同程度的升高, H2O2和MDA含量有不同程度的下降;海马区神经元排列密集有序,细胞间隙减小,神经元细胞形态结构有不同程度的恢复。结论: SP对MPTP诱导的神经元损伤具有神经保护作用,其潜在机制可能是提高脑组织抗氧化能力,减轻氧化应激反应。 相似文献
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根据Inventor三维设计软件的设计功能特征,结合压力机产品的机构特点,进行参数化设计。建立参数化的骨架模型,通过尺寸约束或程序约束的控制,进行工程图纸的生成,指导生产,提高设计效率。 相似文献
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通过X射线衍射.磁测量和M(?)ssbauer谱测定了Nd(Fe1-Cox)10V2的结构和磁性.结果表明,Nd(Fe1-xCox)10V2(x=0,0.05,0.10,0.15,0.20)化合物的晶体结构均为ThMn12型结构;随着 Co含量x的增大,晶格常数将单调减少.Co原子的替代将导致化合物各个Fe晶位上的磁超精细场值Bhf逐渐增加.Co部分取代Nd(Fe1-xCox)10V2中的Fe原子时.将择优占据8i铁晶位.取向样品NdFe10V2的热磁曲线和变温M(?)ssbauer谱研究结果表明.该化合物在T=120K条件下存在自旋重取向现象. 相似文献
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一种数据处理的灰色预测新方法 总被引:1,自引:0,他引:1
针对某些实验数据分散性强的特点 ,若直接用灰色GM (1,1)模型作预测 ,其误差较大。在此提出一种改进的灰色预测模型。首先将原始数据取λ次幂 (0 <λ <1) ,以降低它的分散性。由于λ可依具体情况取不同的值 ,所以比传统的对数据取对数更灵活 ,收敛性更好。然后再用GM (1,1)模型可以得到较好的预测结果。 相似文献
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在判定试验数据具有混沌特性之后 ,利用灰色建模原理与混沌建模原理有机地结合 ,研究了试验数据处理的灰色混沌方法。并给出了两个实例。 相似文献
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灰色系统理论在数控机床误差数据处理中的应用 总被引:2,自引:0,他引:2
根据数控机床误差数据处理的特点,将灰色系统理论首次应用于数控机床误差数据处理中,提出了几何误差数据处理的灰色新陈代谢模型,并给出了模型检验方法,方法简便易行,计算量小。 相似文献
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M. Zebardast A. Karimi Taheri 《Journal of Materials Processing Technology》2011,211(6):1034-1043
In this research, it is shown that the production of bimetallic Al/Cu rod by cold ECAE process is feasible. The mechanism of the cold weld between the copper sheath and aluminum core is assessed using the characteristics of the mating surfaces both theoretically and by examining the SEM micrographs of the peeled surfaces. It is shown that the stretch produced by the shear strain in the process leads to the fracture of the work-hardened layer of the mating surfaces and then by extruding the virgin metal through the cavities of the cracks a cold weld is developed between the sheath and core of the rod. To achieve the cold weld, a threshold surface stretch of about 59% is required. It is shown that the decrease in die angle leads to a higher welding strength. Moreover, the presence of outer angle (ψ) impairs the quality of the weld. 相似文献
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The GalnAsSb quaternary alloys for 2~4 μm long wavelength optoelectronics have been prepared byMOCVD.The growth of buffer layers and the employment of GaSb/GaAs and GaSb/GaSb hybridsubstrates are mentioned,which effectively improve the properties of GalnAsSb epilayers.In order to controlthe epitaxial growth of GaSb and GalnAsSb,emphasis is given on the deposition rates,growth temperaturesand the relationship between growth conditions and the distribution coefficients of In and Sb.The experimen-tal solid compositions in this work are predicted by the thermodynamic calculations.Whether the growth ofGalnAsSb epilayers is controlled by chemical reactions or by mass diffusions depends on growth temperatures.This argument is verified by kinetic considerations.The FWHMs of the DCXD (double crystal X-raydiffraction)spectra of GalnAsSb epilayers grown on GaSb/GaSb and GaSb/GaAs hybrid substrates areabout 200~300 arcsec and 800 arcsec respectively.The unintentionally doped GalnAsSb epilayers have themobilities of μp=100~240 cm~2/V·s at 300 K.The corresponding wavelength ofMOCVD GaInAsSb alloysis calculated from EPMA(electronic probe microanalysis)data and determined by FTIR(Fourier transformedinfrared spectroscopy)measurement. 相似文献
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The nanosized Ba(CoxNb1–x)O3(BCN) particles were prepared under high temperature and pressure conditions by precipitation from metal nitrates with aqueous potassium hydroxide. Ba(CoxNb1–x)O3 powders were obtained in the temperature range of 170–210 °C for 6 h. The results show that the average size of the synthesized particles increases with increasing reaction temperature. The average size of the synthesized particles is about 10 nm. The crystalline phase of the synthesized particles is found to be Ba(CoxNb1–x)O3. Ceramics derived from the nano BCN powders could achieve high sintering density at a relatively low sintering temperature. 相似文献