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991.
波纹圆孔光栏的衍射及其设计 总被引:2,自引:1,他引:1
详细研究了波纹光珠菲涅耳衍射特征,提出并论证了调幅正弦波纹光栏级在较大的菲涅耳数范围内有效地抑制光束中央部分的衍射调制,并给出这类波纹光栏用于高功率光系统的设计程序。 相似文献
992.
Y.M. Zhan 《Journal of sound and vibration》2005,286(3):451-476
Parametric time-frequency representation based on parametric models is more desirable for presenting highly precise time-frequency domain information due to its high-resolution property. However, the sensitivity and robustness of parametric models, in particular the parametric models on the basis of advanced adaptive filtering algorithms, has never been investigated for on-line condition monitoring of rotating machinery. Part 1 of this study proposed three adaptive parametric models based on three advanced adaptive filtering algorithms. Part 2 of this study is concerned with the effectiveness of the proposed models under distinct gear states, especially the highly non-stationary conditions accrued from advanced gear faults. Four gear states are considered: healthy state, adjacent gear tooth failure, non-adjacent gear tooth failure and distributed gear tooth failure. The vibration signals used in this study include the time-domain synchronous averaging signal and gear motion residual signal for each considered gear state. The test results demonstrate that the optimum filter behavior can readily be attained and the white Gaussian assumption of innovations can relatively be easily guaranteed for the NAKF-based model under distinct gear states and a wide variety of model initializations. On the other hand, the EKF- and MEKF-based models are capable of generating more accurate time-frequency representations than the NAKF-based model, but in general the optimality condition for white Gaussian assumption cannot be guaranteed for these two advanced models. Therefore, the NAKF-based model is preferred for automatic condition monitoring due to its appealing robustness to distinct gear states and arbitrary model initializations, whereas the EKF- and MEKF-based models are desirable when accurate time-frequency representation is concerned. 相似文献
993.
994.
Ya-fei Yu Jian Feng Xiao-qing Zhou Ming-sheng Zhan 《International Journal of Theoretical Physics》2004,43(1):21-26
We construct a quantum machine which, by using an asymmetric cloner, disentangles an entangled state and nearly retains it. The attainable maximum value of the scaling parameter for disentangling is identical to that obtained in previous works. The fidelity of the output residual entangled state with respect to the input entangled state is state-dependent. The result shows that it is possible to deal with disentanglement and broadcasting entanglement in a single unitary evolution. 相似文献
995.
推广了著名的Boutroux—Cartan定理。设aμ(μ=1,2,…,n)为复平面上任意的n个点,H为任意的一个正数,则在平面上同时使得n∏μ=1 |z-aμ|≤(H/e)^n和n∑μ=1 1/|z-aμ|≥nlog(en)/H成立的点z可被含于总数不超过n,半径总和不超过2H的一组圈内。 相似文献
996.
997.
998.
In this paper, we propose a protocol which can realize quantum cloning of an unknown tripartite entangled state and its orthogonal
complement state with assistance from a state preparer. The first stage of the protocol requires usual teleportation via three
entangled particle pairs as quantum channel. In the second stage of the protocol, the perfect copies and complement copies
of an unknown state can be produced with the assistance (through a tripartite projective measurement) of the state preparer.
We also present a scheme for the teleportation by using non-maximally entangled quantum channel. It is shown that the clones
and complement clones of the unknown state can be obtained with certain probability in the latter scheme. 相似文献
999.
Jian-Ping Zhou Hong-Cai He Yi Zhang Chao-Yong Deng Zhan Shi Ce-Wen Nan 《Applied Physics A: Materials Science & Processing》2007,89(2):553-558
CoFe2O4 (CFO) thin film with highly (111)-preferential orientation was first deposited on the silicon substrate by a pulsed-laser
deposition, and then Pb(Zr0.52Ti0.48)O3 (PZT) layers were deposited with different oxygen pressures to form the bilayer CFO/PZT nanocomposite thin films. X-ray diffraction
showed that the PZT preferential orientation was strongly dependant on the oxygen pressure. The smooth film surface was obtained
after depositing the CFO and PZT layers. The bilayer thin films exhibit good ferromagnetic and ferroelectric properties, and
a low leakage current density of 0.004 μA/cm2 at 50 kV/cm. The leakage current density curves show loops for the electric polarized field when the electric field reverses.
PACS 77.84.Lf; 75.80+q; 81.05.Zx; 81.15.Fg 相似文献
1000.
This paper has observed linewidth narrowing of dark states in rubidium cell by using the Hanle configuration. The reduction of the coherent resonance width under the transition of ^87Rb Fg = 1 → Fe = 0 is observed and the qualitative explanation about its mechanism is presented. Multiple subnatural width dips are obtained with a linearly polarized laser beam for the transitions of ^87Rb Fg = 1→Fe = 0, 1, 2. The feature of negative and positive slope, namely dispersionlike feature, is observed in the transmitted light. 相似文献