The Experts below are selected from a list of 51 Experts worldwide ranked by ideXlab platform
Sun Fucheng - One of the best experts on this subject based on the ideXlab platform.
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diagnostic ultrasound image subtraction based hifu effect estimation method by using wavelet Decomposition Coefficient energy
International Conference on Biomedical Engineering, 2007Co-Authors: Feng Yanling, Chen Zhencheng, He Jishan, Sun FuchengAbstract:This study tests the hypothesis that the effect of High-Intensity Focused Ultrasound (HIFU) can be correlated with the texture feature of general ultrasound image subtraction (USIS). Porcine muscle was chosen as in-vitro sample. Tissue's ultrasound images and their relative temperature values were caught during experiment. We calculate the wavelet Decomposition Coefficient energy (WDCE) of USIS of the HIFU lesion area to analysis texture features at different temperature. The statistical results show that WDCE elevates linearly with the temperature especially under 65°C. We still analyzed the WDCE of rotation-invariant subbands. Between 40°C to 65°C, the subband WDCEs elevate linearly with temperature, but they will not change much above 65°C. So we get a conclusion that WDCE can be used as a parameter for estimating the temperature during HIFU treatment and subband WDCEs are helpful to monitor the HIFU effect non-invasively.
Werner Hanagarth - One of the best experts on this subject based on the ideXlab platform.
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litter fall litter stocks and Decomposition rates in rainforest and agroforestry sites in central amazonia
Nutrient Cycling in Agroecosystems, 2004Co-Authors: Christopher Martius, Marcos Valerio Garcia, Hubert Höfer, Jorg Rombke, Werner HanagarthAbstract:The sustainability of agroforestry systems in Amazonia was assessed from their litter dynamics and Decomposition. Litter fall and litter stocks were determined from July 1997 to March 1999 in four sites in central Amazonia: a primary rainforest, a 13-year-old secondary forest, and two sites of a polyculture forestry system which consisted of four planted tree species of commercial use amidst upcoming secondary growth. The average annual litter fall in the undisturbed primary rainforest (FLO) was 8.4 t ha−1 year−1, which is within the range of litter fall in other rainforests in the region. It was similar in one of the two polyculture sites (8.3 t ha−1 year−1), but lower in the secondary forest and in the second polyculture site. In the litter fall in secondary forest and agroforestry sites, the leaf portion was higher (76–82% of total litter fall) than in FLO, due to reduced fine matter and wood fall. Leaf litter fall variability was much lower in the plantation sites than in the forests, which is explained by the much more homogeneous stand structure of the plantations. The quality of the produced litter, measured as C/N ratio, differed significantly between the primary forest site and one polyculture and the secondary forest site. The cumulative input of nitrogen through litter fall was 144 kg ha−1 year−1 in FLO, and 91–112 kg ha−1 year−1 in the polycultures and the secondary forest. Litter fall was not correlated with soil parameters, but had a significant linear regression with canopy closure. For the primary rainforest, litter fall was also (inversely) correlated with monthly rainfall. Litter fall was higher in the first year (1997–1998; an El Nino period) than in 1998–1999. Litter stocks on the forest floor were highest in the secondary forest (24.7 t ha−1), and much lower in the polyculture sites (15.1–16.2 t ha−1) and the primary forest (12.0 t ha−1). There were no differences in the relative N content (C/N ratio) of the litter stocks between the sites, but the larger stocks led to higher absolute N contents in the litter layer in the secondary forest. From the monthly values of litter stocks (S) and litter fall (P), the Decomposition Coefficient ke=P/S was calculated, which was, on average, highest for the primary forest (0.059), followed by the polyculture systems (0.040–0.042), and by the secondary forest (0.024). Thus, due to low Decomposition rates, the secondary forest site showed large litter accumulations in spite of a relatively low litter fall. In contrast, the primary forest showed high litter fall but low stocks, due to high Decomposition rates. The Decomposition Coefficients of the polyculture systems ranged between the primary and the secondary forest. The reduced Decomposition rates in the man-managed agroecosystems indicate quantitative and/or qualitative changes in the decomposer communities of these systems that lead to a higher build-up of litter stocks on the forest floor. However, the decomposer systems in the polyculture sites still were more functional than in the site of non-managed secondary growth. Thus, from a soil biological viewpoint, ecologically sustainable low-input agroforestry in Amazonia will benefit from the application of these polyculture systems.
Huo Baichao - One of the best experts on this subject based on the ideXlab platform.
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transmission lines fault recognition method based on multi wavelet packet Coefficient entropy and artificial neural network
Power system technology, 2008Co-Authors: Huo BaichaoAbstract:Based on the Decomposition Coefficient of multi-wavelet packet and the concept of information entropy the expression of multi-wavelet packet Coefficient entropy (MPCE) is defined,and the method to recognize fault types of transmission lines by combining multi-wavelet packet Coefficient entropy with artificial neural network (ANN) is proposed. First,the fault current signals sampled under various fault conditions are decomposed by multi-wavelet packet properly and the Coefficient entropies of different frequency bands are calculated; then the eigenvectors of multi-wavelet packet are constructed,and taking these eigenvectors as training samples the radial basis function (RBF) neural network is trained; when fault occurs in transmission line,the fault type recognition can be implemented by inputting the extracted MPCE eigenvector of fault current signal into the trained RBF neural network. Simulation results show that there is more fault current characteristic information extracted by multi-wavelet packet than that extracted by traditional wavelet packet and a better training result of ANN by MPCE eigenvectors can be obtained,meanwhile,the recognition precision of network is better than that by traditional wavelet packet.
Akitsu Kazuyuki - One of the best experts on this subject based on the ideXlab platform.
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Minimum variance estimation of galaxy power spectrum in redshift space
'Oxford University Press (OUP)', 2020Co-Authors: Shiraishi Maresuke, Okumura Teppei, Sugiyama, Naonori S., Akitsu KazuyukiAbstract:We study an efficient way to enhance the measurability of the galaxy density and/or velocity power spectrum in redshift space. It is based on the angular Decomposition with the Tripolar spherical harmonic (TripoSH) basis and applicable even to galaxy distributions in wide-angle galaxy surveys. While nontrivial multipole-mode mixings are inevitable in the covariance of the Legendre Decomposition Coefficient commonly used in the small-angle power spectrum analysis, our analytic computation of the covariance of the TripoSH Decomposition Coefficient shows that such mixings are absent by virtue of high separability of the TripoSH basis, yielding the minimum variance. Via the simple signal-to-noise ratio assessment, we confirm that the detectability improvement by the TripoSH Decomposition approach becomes more significant at higher multipole modes, and, e.g., the hexadecapole of the density power spectrum has two orders of magnitude improvement. The TripoSH Decomposition approach is expected to be applied to not only currently available survey data but also forthcoming wide-angle one, and to bring about something new or much more accurate cosmological information.Comment: 5 pages, 1 figure, 1 table; version matching publication in MNRAS Letter
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Minimum variance estimation of statistical anisotropy via galaxy survey
2020Co-Authors: Shiraishi Maresuke, Okumura Teppei, Akitsu KazuyukiAbstract:We argue whether it is beneficial to measure cosmic statistical anisotropy from redshift-space correlators of the galaxy number density fluctuation and the peculiar velocity field without adopting the plane-parallel (PP) approximation. Since the correlators are decomposed using the general tripolar spherical harmonic (TripoSH) basis, we can deal with wide-angle contributions untreatable by the PP approximation, and at the same time, target anisotropic signatures can be cleanly extracted. We, for the first time, compute the covariance of the TripoSH Decomposition Coefficient and the Fisher matrix to forecast the detectability of statistical anisotropy. The resultant expression of the covariance is free from nontrivial mixings between each multipole moment caused by the PP approximation and hence the detectability is fully optimized. Compared with the analysis under the PP approximation, the superiority in detectability is always confirmed, and it is highlighted, especially in the cases that the shot noise level is large and that target statistical anisotropy has a blue-tilted shape in Fourier space. The application of the TripoSH-based analysis to forthcoming all-sky survey data could result in constraints on anisotropy comparable to or tighter than the current cosmic microwave background ones.Comment: 19+1 pages, 3 figure
Feng Yanling - One of the best experts on this subject based on the ideXlab platform.
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diagnostic ultrasound image subtraction based hifu effect estimation method by using wavelet Decomposition Coefficient energy
International Conference on Biomedical Engineering, 2007Co-Authors: Feng Yanling, Chen Zhencheng, He Jishan, Sun FuchengAbstract:This study tests the hypothesis that the effect of High-Intensity Focused Ultrasound (HIFU) can be correlated with the texture feature of general ultrasound image subtraction (USIS). Porcine muscle was chosen as in-vitro sample. Tissue's ultrasound images and their relative temperature values were caught during experiment. We calculate the wavelet Decomposition Coefficient energy (WDCE) of USIS of the HIFU lesion area to analysis texture features at different temperature. The statistical results show that WDCE elevates linearly with the temperature especially under 65°C. We still analyzed the WDCE of rotation-invariant subbands. Between 40°C to 65°C, the subband WDCEs elevate linearly with temperature, but they will not change much above 65°C. So we get a conclusion that WDCE can be used as a parameter for estimating the temperature during HIFU treatment and subband WDCEs are helpful to monitor the HIFU effect non-invasively.
