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991.
针对自动控制系统的设计很大程度上还依赖于实际系统的反复实验、调整的普遍现象,结合具体的设计实例,介绍了利用较先进的MATLAB软件中的SIMULINK仿真工具来实现对自动控制系统建模、分析与设计、仿真的方法。它能够直观、快速地分析系统的动态性能、和稳态性能。并且能够灵活的改变系统的结构和参数,通过快速、直观的仿真达到系统的优化设计。 相似文献
992.
993.
Low-cycle fatigue behavior of two magnesium alloys 总被引:2,自引:0,他引:2
Feng Li Yue Wang Lijia Chen Zheng Liu Jiyang Zhou 《Journal of Materials Science》2005,40(6):1529-1531
994.
Dong-Li Shi Xi-Qiao Feng Hanqing Jiang Yonggang Y. Huang Keh-Chih Hwang 《International Journal of Fracture》2005,134(3-4):369-386
Due to the enormous difference in the scales involved in correlating the macroscopic properties with the micro- and nano-physical
mechanisms of carbon nanotube-reinforced composites, multiscale mechanics analysis is of considerable interest. A hybrid atomistic/continuum
mechanics method is established in the present paper to study the deformation and fracture behaviors of carbon nanotubes (CNTs)
in composites. The unit cell containing a CNT embedded in a matrix is divided in three regions, which are simulated by the
atomic-potential method, the continuum method based on the modified Cauchy–Born rule, and the classical continuum mechanics,
respectively. The effect of CNT interaction is taken into account via the Mori–Tanaka effective field method of micromechanics.
This method not only can predict the formation of Stone–Wales (5-7-7-5) defects, but also simulate the subsequent deformation
and fracture process of CNTs. It is found that the critical strain of defect nucleation in a CNT is sensitive to its chiral
angle but not to its diameter. The critical strain of Stone–Wales defect formation of zigzag CNTs is nearly twice that of
armchair CNTs. Due to the constraint effect of matrix, the CNTs embedded in a composite are easier to fracture in comparison
with those not embedded. With the increase in the Young’s modulus of the matrix, the critical breaking strain of CNTs decreases. 相似文献
995.
冯桑 《广东工业大学高等工程教育研究》2005,5(B09):80-83
文章提出了“车辆工程”专业应在原有的“汽拖”和“汽运”专业的基础上充分融合发展,积极面向整个汽车产业链,办成一个跨学科的崭新专业,培养具有较强就业竞争力的复合型人才。 相似文献
996.
997.
Feng Li 《Materials Research Bulletin》2005,40(8):1244-1255
In this paper, a series of pure Ni1 − xZnxFe2O4 (0 ≤ x ≤ 1) spinel ferrites have been synthesized successfully using a novel route through calcination of tailored hydrotalcite-like layered double hydroxide molecular precursors of the type [(Ni + Zn)1 − x − yFey2+Fex3+(OH)2]x+(SO42−)x/2·mH2O at 900 °C for 2 h, in which the molar ratio of (Ni2+ + Zn2+)/(Fe2+ + Fe3+) was adjusted to the same value as that in single spinel ferrite itself. The physico-chemical characteristics of the LDHs and their resulting calcined products were investigated by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and Mössbauer spectroscopy. The results indicate that calcination of the as-synthesized LDH precursor affords a pure single Ni1 − xZnxFe2O4 (0 ≤ x ≤ 1) spinel ferrite phase. Moreover, formation of pure ferrites starting from LDHs precursors requires a much lower temperature and shorter time, leading to a lower chance of side-reactions occurring, because all metal cations on the brucite-like layers of LDHs can be uniformly distributed at an atomic level. 相似文献
998.
Magnetic tunnel junctions (MTJs) with amorphous CoFeB and Co/sub 2/MnSi electrodes were fabricated and examined. In the case of [Co/sub 90/Fe/sub 10/]/sub 100-x/B/sub x/, the x=32% boron addition reduces the magnetization by 30% compared to Co/sub 90/Fe/sub 10/, yet the reduction of the tunnel magnetoresistance (TMR) is over 95%. On the contrary, in the case of Co/sub (100-x-y)/Mn/sub x/Si/sub y/, although net magnetization is very small at room temperature, the TMR can be as large as 7%. The character of each metalloid (boron and silicon) could be responsible for the peculiar behavior to each system. 相似文献
999.
Yufeng Su Hong Wang Guifu Ding Feng Cui Weiping Zhang Wenyuan Chen 《IEEE transactions on magnetics》2005,41(12):4380-4383
We describe the preparation of CoNiMnP-based permanent-magnet material using several sulfate and chloride solutions. We studied eight samples, and all the samples show vertical magnetic anisotropy. Sample8, which was electroplated from a low-concentration chloride solution and under external magnetic field, demonstrates the best magnetic properties with coercivity 2632 Oe, remanence 0.20 T, and maximum magnetic energy 10.185 kJ/m/sup 3/. An array structure can avoid the stress between the electroplated layer and the seed layer. The electroplated Co/sub 0.8/Ni/sub 0.1174/Mn/sub 0.0062/P/sub 0.0762/ permanent magnet has potential for bidirectional actuators in micro-electromechanical systems. 相似文献
1000.