In this paper, the inverse problem of reconstructing reflectivity function of a medium is examined within a blind deconvolution framework. The ultrasound pulse is estimated using higher-order statistics, and Wiener fi...In this paper, the inverse problem of reconstructing reflectivity function of a medium is examined within a blind deconvolution framework. The ultrasound pulse is estimated using higher-order statistics, and Wiener filter is used to obtain the ultrasonic reflectivity function through wavelet-based models. A new approach to the parameter estimation of the inverse filtering step is proposed in the nondestructive evaluation field, which is based on the theory of Fourier-Wavelet regularized deconvolution (ForWaRD). This new approach can be viewed as a solution to the open problem of adaptation of the ForWaRD framework to perform the convolution kernel estimation and deconvolution interdependently. The results indicate stable solutions of the esti- mated pulse and an improvement in the radio-frequency (RF) signal taking into account its signal-to-noise ratio (SNR) and axial resolution. Simulations and experiments showed that the proposed approach can provide robust and optimal estimates of the reflectivity function.展开更多
Digital data of precursors is noted for its high accuracy. Therefore, it is important to extract the high frequency information from the low ones in the digital data of precursors and to discriminate between the trend...Digital data of precursors is noted for its high accuracy. Therefore, it is important to extract the high frequency information from the low ones in the digital data of precursors and to discriminate between the trend anomalies and the short-term anomalies. This paper presents a method to separate the high frequency information from the low ones by using the wavelet transform to analyze the digital data of precursors, and illustrates with examples the train of thoughts of discriminating the short-term anomalies from trend anomalies by using the wavelet transform, thus provide a new effective approach for extracting the short-term and trend anomalies from the digital data of precursors.展开更多
Land use, land-use change and forestry （LULUCF） activities can allow Annex I parties in the Kyoto Protocol to decrease their carbon emission reduction pressure, and comparably expanding more emission space for their...Land use, land-use change and forestry （LULUCF） activities can allow Annex I parties in the Kyoto Protocol to decrease their carbon emission reduction pressure, and comparably expanding more emission space for their domestic industries and energy production. The loopholes resulted from LULUCF activity types and specific accounting methods are always argued among the different parties, particularly including harvested wood products, influences of force majeure, threshold values of the reference level, and gross-net or net-net accounting methods. For estimating uncertainties in accounting loopholes, and to avoid that developed countries take advantage of the account{ng loopholes of LULUCF to decrease their emission reduction pressure, the LULUCF data submitted from the main developed countries in Annex I, including EU 27, Canada, Japan, and Russia, were collected. According to the analysis of these data, the loopholes influence the accounting results of LULUCF. The results show that the uncertainty of harvested wood products is excessive. The carbon sink produced by LULUCF activities will increase averagely by at least 30% without force majeure. The threshold values of the reference level of carbon sink should be set to a higher level. The net-net accounting method might be more suitable for LULUCF after 2012.展开更多
基金Project (No. PRC 03-41/2003) supported by the Ministry of Con-struction of Cuba
文摘In this paper, the inverse problem of reconstructing reflectivity function of a medium is examined within a blind deconvolution framework. The ultrasound pulse is estimated using higher-order statistics, and Wiener filter is used to obtain the ultrasonic reflectivity function through wavelet-based models. A new approach to the parameter estimation of the inverse filtering step is proposed in the nondestructive evaluation field, which is based on the theory of Fourier-Wavelet regularized deconvolution (ForWaRD). This new approach can be viewed as a solution to the open problem of adaptation of the ForWaRD framework to perform the convolution kernel estimation and deconvolution interdependently. The results indicate stable solutions of the esti- mated pulse and an improvement in the radio-frequency (RF) signal taking into account its signal-to-noise ratio (SNR) and axial resolution. Simulations and experiments showed that the proposed approach can provide robust and optimal estimates of the reflectivity function.
文摘Digital data of precursors is noted for its high accuracy. Therefore, it is important to extract the high frequency information from the low ones in the digital data of precursors and to discriminate between the trend anomalies and the short-term anomalies. This paper presents a method to separate the high frequency information from the low ones by using the wavelet transform to analyze the digital data of precursors, and illustrates with examples the train of thoughts of discriminating the short-term anomalies from trend anomalies by using the wavelet transform, thus provide a new effective approach for extracting the short-term and trend anomalies from the digital data of precursors.
基金supported by China "973" projects of Special Negotiating Problems for LULUCF Response to Climate Change(No2010CB955702)Space-time Pattern of Carbon and Nitrogen and Water Flux of Chinese Terrestrial Ecosystem and its Regional Response(No 2010CB833504)
文摘Land use, land-use change and forestry （LULUCF） activities can allow Annex I parties in the Kyoto Protocol to decrease their carbon emission reduction pressure, and comparably expanding more emission space for their domestic industries and energy production. The loopholes resulted from LULUCF activity types and specific accounting methods are always argued among the different parties, particularly including harvested wood products, influences of force majeure, threshold values of the reference level, and gross-net or net-net accounting methods. For estimating uncertainties in accounting loopholes, and to avoid that developed countries take advantage of the account{ng loopholes of LULUCF to decrease their emission reduction pressure, the LULUCF data submitted from the main developed countries in Annex I, including EU 27, Canada, Japan, and Russia, were collected. According to the analysis of these data, the loopholes influence the accounting results of LULUCF. The results show that the uncertainty of harvested wood products is excessive. The carbon sink produced by LULUCF activities will increase averagely by at least 30% without force majeure. The threshold values of the reference level of carbon sink should be set to a higher level. The net-net accounting method might be more suitable for LULUCF after 2012.
