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1.
摩擦强度对薄膜表面形态的作用:原子力显微镜下的观察 总被引:2,自引:2,他引:0
展示了摩擦强度对聚酰亚胺薄膜表面形态的影响,原子力显微图像显示,机械摩擦会使聚酰亚胺薄膜表面上形成微沟槽,这些沟槽的表面具有丰富的表面精细构造。原子显微图像还揭示了机械摩擦可以改变被磨擦聚酰亚胺膜的表面形态。 相似文献
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Melt crystallization of isotactic polypropylene (iPP), containing crystallites of N,N′-dicyclohexyl-2,6-naphthalenedicarboxamide (DCNDCA) as a nucleating agent of the the β-phase iPP crystal, is carried out under a magnetic field (6 T) to obtain the alignment of the iPP crystal induced by magnetic alignment of DCNDCA. In a previous paper, DCNDCA was reported to undergo magnetic alignment in a liquid suspension. The obtained iPP sample exhibits alignment of the β-phase crystal with the c-axis aligned perpendicular to the magnetic field. The comparison of this alignment of iPP with the reported magnetic alignment of DCNDCA indicates that the β-phase crystal grows epitaxially on the DCNDCA crystal. The (330)β plane of the iPP crystal lies on the bc-plane of the DCNDCA crystal in which the direction of the c-axis of the iPP coincides with the direction of the b-axis of the DCNDCA crystal. 相似文献
4.
Recent developments of high-performance NEOMAX magnets 总被引:6,自引:0,他引:6
For further improvement in achieving extremely high magnetic properties of Nd- Fe- B sintered magnets, extensive investigation
has been done to densify the magnet up to the theoretical value, to increase the volume fraction of the Nd
2Fe14B matrix phase, and to achieve a high degree of alignment. By controlling chemical composition and the amount of constituent
phases,improving particle size distribution, and adopting the isostatic pressing method to get better alignment of fine particles,
we have succeeded in obtaining a high-performance magnet having residual flux density (Br) of 1.495 T (14.95 kG), maximum energy product [(BH)max] of 431 kj/m3 (54.2 MGOe), and intrinsic coercivity (iHc) of 845 kA/m (10.62 kOe). 相似文献
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Fifteen to 20 wt % polyetherimide (PEI) solutions with 1-methyl-2-pyrrolidinone (NMP) were prepared. The electrical conductivity and surface tension of the solutions were determined. The fiber spinning technique of electrospinning was optimized in order to prepare unidirectionally aligned, structurally oriented nanofiber tows. The morphology of the PEI fibers was investigated using field emission scanning electron microscopy (FESEM). The well-aligned fibers with diameters between 0.58 and 0.90 μm (FESEM) were collected by electrospinning 20 wt % PEI solutions with NMP in the range of 8–10 kV onto a target rotating with a surface velocity 9.8 m/s. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
7.
垂直定向液晶光阀及光电特性的研究 总被引:2,自引:0,他引:2
系统地讨论了排列相畸变模式液晶光阀结构,原理和制作,结合实际测试对其等效电路和电学匹配进行了分析,详细讨论了它的光电特性及相互关系,实测的液晶垂直排列方式工作的液晶光阀性能指标为,分辨率大于50lp/mm,白光输入灵敏度为6.77μW/cm^2,响应时间为200ms/300ms,白光输出对比度为200:1。 相似文献
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Experiments have been carried out on relatively wide angle-ply laminate samples with very short gauge lengths. These proved to be very much stronger than samples tested in earlier work, and which form the basis for our present design with these materials. It is highly likely that the early results for strength were more indicative of edge effects than true laminate strength. This is confirmed by data from tests on pressurized tubes. A review of the literature on this shows that such tests produced results which can be an order of magnitude higher than the early laminate tests. Thus our design calculations could well be severely underestimating the potential strength of angle-ply laminates. This may be having serious consequences for the aerospace industry, through the use of design criteria for strength which may be too conservative. Single-fibre experiments may pave the way for more realistic estimates of angle-ply laminate strengths. These indicate that a simple one-third power rule can be used to estimate the potential strength. However, this is purely ad hoc at present, and needs to be put on a firmer footing through both theoretical and experimental studies. Furthermore, if this approach is adopted, edge effects will still have to be allowed for, and estimated on the basis of the aspect ratio of the part. 相似文献
9.
《Information Systems Management》2007,24(2):113-120
Four scenarios for the IS organization of 2020 are described, based on differing assumptions about two drivers: the advances in the reliability of international telecommunications and the value placed on computerization in businesses and society. 相似文献
10.
研究优化惯导系统的可观性能,提高捷联惯导两位置对准的速度,有助于提高导航的准确性和快速性,将水平速度误差和等效陀螺误差作为系统观测量,提出采用静基座下快速两位置对准的新方法.在常规对准方法的基础上,建立了引入陀螺信息的观测方程,用奇异值分解方法分析了新系统可观测性,推出了第一位置可观测量的最优估计及估计误差.根据状态快速收敛的特性,提出采用PCWS方法,对加速度计和陀螺进行了有效的标定,并进行了仿真,结果证明方法有效提高加快了两位置对准的速度,能充分利用陀螺信息,有效提高了惯导系统的可观测性,缩短对准时间,具有重要的参考价值. 相似文献