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321.
This paper finds the appropriate pi-coefficients for a parameter estimation adaptive system and uses them to analyze the stability of two estimation algorithms. The estimation error dynamics of the system are modeled by a linear time-invariant subsystem and a nonlinear time-varying update law in a feedback loop. Then the so-called max-p problems are formulated and solved to obtain the pi-coefficients for the linear subsystem and nonlinear update low. For the investigated system, the quantitative results show that the least-squares update algorithm has larger stability range than that of the gradient algorithm, and the σ-modification scheme gives larger stability ranges for both algorithms. 相似文献
322.
The formation mechanism of the synthesis of MoO3 -doped YSr2 Cu3 O y powders using the citrate process was investigated. It was shown that the precursor phase (Sr1- x Y x )14 Cu24 O41 played a crucial role in forming the superconducting phase. It was found that the precursor phase (Sr1- x Y x )14 Cu24 O41 interacted with water and decomposed when it was heavily milled and heated. 相似文献
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荆江分洪北闸加固工程2号护坦(斜面)混凝土的保温层采用了水泥膨胀珍珠岩砂浆,并对这种材料的保温效果进行了试验研究。试验表明:水泥膨胀珍珠岩砂浆降低最高温差,减小内表温差,缩小表温变幅和防止混凝土表面裂缝效果显著。在北闸2号护坦混凝土表面铺设1万平方米保温层,获得良好效果。 相似文献
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H Wu 《Canadian Metallurgical Quarterly》1996,14(6):328-30, 365-8
A universal EPR simulation program has been created by the author, which is based on the following spin Hamiltonian equation: [equation: see text] where D and E are the axial and rhombic zero-field splitting parameters, respectively. The program can be used for simulation of EPR spectra with half-integer electronic spin (S = n/2, n = 3, 5, 7, 9) systems. In this article, the integer spin (S = n/2, n = 2, 4) systems are also considered. The EPR simulation results show that when D > frequency, no EPR signal can be seen from EPR simulation; when D approximately frequency, whichever X/Q/W-band is used, the EPR signal can be seen on the basis of the simulated EPR results presented. 相似文献
330.
The mild sliding wear behaviour of a 15 vol % Al2O3P/6061 Al composite has been investigated by using a pin-on-disc reciprocating sliding machine. The composite has been shown to exhibit an excellent wear resistance as compared to the unreinforced matrix alloy. The wear rate of the composite under dry wear conditions with a 12N load is approximately one tenth of that in the 6061 aluminium alloy. The wear rate of the composite under lubrication with 15W/40 gear oil under a 100N load is only one thousandth ofthat in the 6061 aluminium alloy.The dry wear resistance of an over-aged sample is shown here to be better than a peak aged or under-aged sample when the composite was aged at 160°C. The coefficient of friction of the composite was approximately 0.5–0.6 under dry conditions and 0.07 in lubricated wear experiments.In the initial stage, the worn surface of the composite under dry conditions is primarily composed of ploughed grooves and ductile tear. The composite makes a conducting contact with the steel pin. The worn surface is composed of compacted powder and the contact potential gradually increases when the period of the wear experiment goes beyond 2 h. 相似文献