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101.
102.
Various wireless systems and the research preceding their practical use in China are described. The topics discussed include research establishments, research and development projects underway, challenges inherent to digital radio, and expansion opportunities afforded by satellite communications 相似文献
103.
104.
105.
W. F. Flanagan Lijun Zhong B. D. Lichter 《Metallurgical and Materials Transactions A》1993,24(3):553-559
A model is proposed to explain transgranular-stress corrosion cracking (T-SCC) in face-centered cubic (fcc) materials. Crack
propagation is shown to be anisotropic, in that growth near {110} < 001> is discontinuous due to crack arrest by dislocation
blunting whereas growth away from this growth orientation is continuous. For the former case, renucleation of arrested cracks
involves active dissolution of shear bands at the crack tip, which changes the stress state at Lomer-Cottrell locks, causing
them to fail by cleavage. Once the crack is nucleated, its instantaneous macroscopic crack-growth velocity is considered to
be comprised of multiple nucleation of microcracks with intervening arrests. This microcracking results from the interaction
of the stress fields from neighboring cracks which are forming simultaneously, the crack-opening constraint due to ligaments
which act as “bridges” behind the crack front, and the localized dissolution at the microcrack tip which affectsK
IC and leads to the “cobblestone” appearance. Experimental evidence and theoretical considerations are presented to support
the model. The system studied was Cu-25 at. pct Au in 0.6 M NaCl solution at potentials between 300 and 400 mV (sce), which
precludes hydrogen embrittlement.
This article is based on a presentation made in the symposium “Quasi-Brittle Fracture” presented during the TMS fall meeting,
Cincinnati, OH, October 21–24, 1991, under the auspices of the TMS Mechanical Metallurgy Committee and the ASM/MSD Flow and
Fracture Committee. 相似文献
106.
In this paper, the complex source-point theory used for a symmetric concave spherical resonator is extended to an asymmetric concave spherical resonator. Thus, the formulae for the field distribution of the asymmetric spherical resonator can be easily deduced from the formulae for the field distribution of the symmetric resonator, thereby the application range of the complex source-point theory is enlarged and a convenient method is provided for the field analysis of an arbitrary spherical resonator. 相似文献
107.
108.
109.
110.
Delay-dependent state estimation for delayed neural networks 总被引:3,自引:0,他引:3
Yong He Qing-Guo Wang Min Wu Chong Lin 《Neural Networks, IEEE Transactions on》2006,17(4):1077-1081
In this letter, the delay-dependent state estimation problem for neural networks with time-varying delay is investigated. A delay-dependent criterion is established to estimate the neuron states through available output measurements such that the dynamics of the estimation error is globally exponentially stable. The proposed method is based on the free-weighting matrix approach and is applicable to the case that the derivative of a time-varying delay takes any value. An algorithm is presented to compute the state estimator. Finally, a numerical example is given to demonstrate the effectiveness of this approach and the improvement over existing ones. 相似文献