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1.
A stochastic model for local disturbances, particularly for a temporal harmonic with random modulations in amplitude and/or phase, is proposed in this paper. Results for the second moment responses of a linear single-degree-of-freedom system to this type of stochastic loading demonstrate a significant change in response characteristics due to a small uncertainty. A local phenomenon may last much longer and resonance may be smeared to a broad range. Integrated with wavelet transform, the proposed approach may be used to model a random process with non-stationary frequency content. Especially, it can be effectively used for Monte Carlo simulation to generate large size of samples that have similar characteristics in time and frequency domains as a pre-selected mother sample has. The technique has a great potential for the case where uncertainty study is warranted but the available samples are limited. 相似文献
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It is shown that direct compression grade tricalcium phosphate yields linear Heckel plots only if the particle density used is that obtained by liquid pycnometry or mercury porosimetry. If the true density is used (i.e. that obtained by gas displacement), then linearization is not obtained in a pressure range where bonding evidently occurs. It is shown that the pore volume in the range of diameters from 0.5 to 2 μm decreases as tableting pressure increases, and that bonding is associated with the loss of pores of this size. 相似文献
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J. H. Elder S. J. D. Prince Y. Hou M. Sizintsev E. Olevskiy 《International Journal of Computer Vision》2007,72(1):47-66
We address the problem of localizing and obtaining high-resolution footage of the people present in a scene. We propose a
biologically-inspired solution combining pre-attentive, low-resolution sensing for detection with shiftable, high-resolution,
attentive sensing for confirmation and further analysis.
The detection problem is made difficult by the unconstrained nature of realistic environments and human behaviour, and the
low resolution of pre-attentive sensing. Analysis of human peripheral vision suggests a solution based on integration of relatively
simple but complementary cues. We develop a Bayesian approach involving layered probabilistic modeling and spatial integration
using a flexible norm that maximizes the statistical power of both dense and sparse cues. We compare the statistical power
of several cues and demonstrate the advantage of cue integration. We evaluate the Bayesian cue integration method for human
detection on a labelled surveillance database and find that it outperforms several competing methods based on conjunctive
combinations of classifiers (e.g., Adaboost). We have developed a real-time version of our pre-attentive human activity sensor
that generates saccadic targets for an attentive foveated vision system. Output from high-resolution attentive detection algorithms
and gaze state parameters are fed back as statistical priors and combined with pre-attentive cues to determine saccadic behaviour.
The result is a closed-loop system that fixates faces over a 130 deg field of view, allowing high-resolution capture of facial
video over a large dynamic scene. 相似文献
9.
In this article, a new algorithm based on an artificial potential field and hierarchical cell decomposition technique is developed to solve the find-path problem for a mobile robot. The complete map of the workspace including obstacle locations is assumed to be known a priori. The basic cell structure used for decomposition is a hexagon. The artificial potential field is based on an attractive force from the goal position and repelling forces from the obstacles. Computer simulations of the algorithm for various obstacle scenarios are also presented. © 1994 John Wiley & Sons, Inc. 相似文献
10.
Two free and one silylated (silane-substituted) photochromic spirooxazines are doped into organically modified ceramics (Ormocer) coatings by sol-gel processing and the thermal decoloration kinetics of these coatings are investigated and compared with the corresponding ethanol solutions and PMMA coatings. The decoloration behaviour of the two free dyes (SO-1 and SO-2) in the Ormocer coatings is similar to that in ethanol solutions, obeying a first-order mechanism and possessing almost the same decoloration rates as in ethanol. This suggests that the dye molecules encapsulated within the pores of the solid matrix are as free as those in ethanol solutions. The silylated dye (SO-3) in the Ormocer coatings, however, exhibits a considerably lower decoloration rate than the corresponding free dye (SO-1) and evident deviation from the first-order mechanism. This indicates apparently that the degree of freedom of the dye molecules is reduced by the silylation. These results are discussed on the basis of solvent polarity, porous structure of the Ormocer coating, and the dye-to-matrix connectivity. 相似文献