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91.
R. Novina 《Chromatographia》1982,15(11):704-706
Summary A method has been developed using gas chromatography — electron impact mass spectrometry for the determination of the di-0-isopropylidene-sorbofuranose and mono-0-isopropylidene-sorbofuranose. The compounds are separated as their trimethylsilyl derivatives on a capillary column coated with the stationary phase SE-52. The mass spectra show that the silylation reaction is quantitiative and that the isopropylidene groups does not change. 相似文献
92.
93.
Near Best Tree Approximation 总被引:2,自引:0,他引:2
Baraniuk R.G. DeVore R.A. Kyriazis G. Yu X.M. 《Advances in Computational Mathematics》2002,16(4):357-373
Tree approximation is a form of nonlinear wavelet approximation that appears naturally in applications such as image compression and entropy encoding. The distinction between tree approximation and the more familiar n-term wavelet approximation is that the wavelets appearing in the approximant are required to align themselves in a certain connected tree structure. This makes their positions easy to encode. Previous work [4,6] has established upper bounds for the error of tree approximation for certain (Besov) classes of functions. This paper, in contrast, studies tree approximation of individual functions with the aim of characterizing those functions with a prescribed approximation error. We accomplish this in the case that the approximation error is measured in L
2, or in the case p2, in the Besov spaces B
p
0(L
p
), which are close to (but not the same as) L
p
. Our characterization of functions with a prescribed approximation order in these cases is given in terms of a certain maximal function applied to the wavelet coefficients. 相似文献
94.
Design of a Thin Film Infrared Barcode on a Flexible Substrate 总被引:1,自引:0,他引:1
Brian Monacelli Dale Kotter Glenn D. Boreman 《International Journal of Infrared and Millimeter Waves》2004,25(2):317-325
We report the design, fabrication and characterization of an infrared barcode. This barcode is composed of a bilayer of titanium and amorphous silicon on a flexible Kapton substrate. Information encoded in the barcode shows high contrast when viewed with an infrared imaging system in the 8 to 12 m spectral region. The barcode information is concealed under visible viewing conditions, i.e., the barcode appears as an untreated, uniform metal sheet to a detector of visible radiation (400 to 700nm). 相似文献
95.
The shift-tolerance property of the encrypted image or the Fourier decrypting key in the Fourier space is proposed based on a phase-encoded virtual image. The encrypted data is obtained by the Fourier transform of the product of a phase-encoded virtual image to camouflage the original one and a random phase image. Therefore, even if unauthorized users analyze the encrypted image, they cannot reconstruct the required image. This virtual image protects the original one from being counterfeited and from unauthorized access. We demonstrate the robustness to data loss and shift of the encrypted data or the Fourier decrypting key in the proposed decryption technique using an interferometer. 相似文献
96.
We present the study of angular selectivity for holographic multiplexing based on random phase encoding by a ground glass. The rotational selectivity of the volume hologram is calculated theoretically and coincides with the experimental measurement. By controlling the parameters including rotational center, effective numerical aperture of both volume hologram and the ground glass, we can obtain different rotational selectivity applied to random phase encoding in volume holographic storage. 相似文献
97.
98.
99.
Alakes Maiti Bibek Patra G.P. Samanta 《International Journal of Mathematical Education in Science & Technology》2013,44(8):1061-1076
The present article deals with the problem of combined harvesting of a
Michaelis–Menten-type ratio-dependent predator–prey system. The
problem of determining the optimal harvest policy is solved by invoking
Pontryagin's Maximum Principle. Dynamic optimization of the harvest policy is
studied by taking the combined harvest effort as a dynamic variable. Computer
simulations are carried out to illustrate our analytical findings. Biological
and bioeconomical interpretations of the results are explained critically. 相似文献
100.
为解决单一的小波神经网络预测精度不高的问题,提出一种新的基于小波去噪和WNN-ARIMA组合模型,应用小波阈值去噪法对小波神经网络的输入值进行预处理,同时对模型残差值进行ARIMA模型修正.利用该组合模型对洮河流域下巴沟站年径流量进行预测,预测趋势和预测值与原始实测数据吻合度高,表明此组合模型可靠性强,可以有效预测年径... 相似文献