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31.
鄂钢电炉炼钢厂在生产60Si2Mn弹簧圆钢时,发生较为严重的机械性能不合,主要表现为延伸率及断面收缩率低,试样呈脆性断口,断口及低倍试样中发现有白点缺陷.经分析,造成60Si2Mn弹簧圆钢机械性能不合的主要原因为钢中氢含量高,在工艺中提出改进措施,以改进其机械性能,提高产品质量. 相似文献
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Optimal bounded control of harmonically and stochastically excited strongly nonlinear oscillators 总被引:1,自引:0,他引:1
A procedure for designing optimal bounded control to minimize the response of harmonically and stochastically excited strongly nonlinear oscillators is proposed. First, the stochastic averaging method for controlled strongly nonlinear oscillators under combined harmonic and white noise excitations using generalized harmonic functions is introduced. Then, the dynamical programming equation for the control problem of minimizing response of the systems is formulated from the partially completed averaged Itô equations by using the dynamical programming principle. The optimal control law is derived from the dynamical programming equation and control constraint without solving the dynamical programming equation. Finally, the stationary probability density of the amplitude and mean amplitude of the optimally controlled systems are obtained from solving the reduced Fokker–Planck–Kolmogorov equation associated with fully completed averaged Itô equations. An example is given to illustrate the proposed procedure and the results obtained are verified by using those from digital simulation. 相似文献
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35.
Zhiping Sun Rulin Zuo Cong Li Baoluo Shen Jing Yan Sijiu Huang 《Materials Characterization》2004,53(5):403-409
High chromium white irons solidify with a substantially austenitic matrix supersaturated with chromium and carbon. The subcritical heat treatment can destabilize the austenite by precipitating chromium-rich secondary carbides and other special carbides. In the as-cast condition the eutectic carbides are (Fe,Cr)7C3 and (Fe4.3Cr2.5Mo0.1)C3. The initial secondary carbide precipitated is (Fe,Cr)23C6 after heat-treating at 853 K for 10 h. There are MoC, Fe2MoC and -carbide precipitating, and (Fe,Cr)23C6 transforms to M3C after 16 h at 853 K. The -carbide and (Fe,Cr)23C6 accomplish transformation to M3C and the matrix changes from martensitic to pearlitic after 22 h at 853 K. Thereby, in the subcritical heat treatment process, the initial secondary carbide precipitated is (Fe,Cr)23C6, followed by -carbide, MoC and Fe2MoC. In addition, there are two in situ transformations from (Fe,Cr)23C6 and -carbide to M3C carbides. 相似文献
36.
Effects of Rare Earth and Alkaline Earth on Spheroidizing of Eutectic Carbides in Low Tungsten White Cast Iron 总被引:3,自引:0,他引:3
Tungsten Alloy White Cast Iron(TAWCI) has great brittleness and narrow application scope. The influences of Rare earth element(Ce) and alkaline earth elements ( K, Na) on the microstructures and performances of TAWCI were researched, and the idea estimating spheroidizing effect of carbides using Circular Degree (C. D) were put forward. The result shows that eutectics carbide tums into sphericity from network after modification, and carbide is refined and uniformly distributed and the C. D of eutectic carbide increases. The mechanism of carbide spheroidizing was analyzed. The impact toughness and wear resistance of TAWCI obviously improve with the rise of C. D of carbides.The service life of modified TAWCI roll is 35 % higher than that of high chromium cast iron roll, and its production cost is reduced by 25 %. 相似文献
37.
Reiji Hattori Shuhei Yamada Yoshitomo Masuda Norio Nihei 《Journal of the Society for Information Display》2004,12(1):75-80
Abstract— We have developed new powder materials that exhibit liquid behavior, which can lead to the realization of novel bistable and reflective displays having paper‐white appearance, high contrast, and quick response. Two types of display were demonstrated, one had 160 × 160 array of pixels and the other had 320 × 320 in a 3.1‐in.‐diagonal viewable image size corresponding to 66 and 132 dpi, respectively. These displays were driven by passive‐matrix addressing. The displays showed a reflectivity of more than 41%, a contrast more than 1:10, and a pixel response time of less than 0.2 msec. The seven‐segment display for use in clocks was also demonstrated. 相似文献
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提出一种有效的具有未知系统伯差的自适应Kalman平滑器.应用状态空间方法和ARMA新息模型,基于白噪声估值器和输出预报器,给出线性离散定常系统自适应最优状态和偏差联合Kalmau平滑器,最后给出仿真实例. 相似文献
40.
本文以线性结构体系在白噪声激发下随机振动离散分析方法为基础,对线性结构体系在有色噪声激发下的随机振动离散分析方法进行了研究。给出均值、均方响应的离散递推式.并为了能在计算机上进行实际运算,给出了实用化计算公式,最后用该方法对一结构进行了实际计算,分析了计算结果。 相似文献