In order to utilize AVO information to inverse lithology parameters and to predict the reservoir bed effectively, the state of the art and the mainly progresses about P-SV converted-wave AVO methods are presented thoroughly in this paper. Furthermore, we review and discuss the basic assumptions and features of several classical formulas, as well as the aspects on parameter inversion for the corresponding approximation. At the same time, we also give two new approximation equations of P-SV wave reflection coefficient and discuss the methods of AVO analysis and parameters inversion by using the new formulae. It is found that the mainly purpose of each approximation is to improve the precision and to emphasize the influence of different elastic parameters, the role that each formula plays in parameter inversion. Also found is that from the relationship of elastic parameters to velocities one can transform one approximation to the others. Further, the all PP wave and P-SV wave reflection coefficients presently can be unified as power series of ray parameter. The conclusions of the present paper should be significant for AVO theory research and parameter inversion.
In order to verify the superiority and effectiveness of extracting rice information based on UAV images. This paper takes the rice plot as the research object, and uses the portable UAV Mavic Pro for aerial photography. Preprocess the acquired UAV images to generate orthophotos with a resolution of 3.95cm/pix. Using object-oriented thinking, visual evaluation and ESP tools are combined to quickly select the optimal segmentation scale to be 300, and support is applied. Vector machine, random forest, and nearest neighbor supervised classification methods have carried out ground object classification and rapid extraction of rice area. The classification results and area accuracy are evaluated by visual classification results. The method with the highest overall accuracy is the nearest neighbor classification method. At this time, the user accuracy of rice classification is 95%, and the area consistency accuracy is 99%. The results show that UAV remote sensing and automatic classification can quickly obtain high resolution images and extract rice planting area in plain rice planting area, make up for the lack of ground survey data when Nongshan is blocked, and provide samples and verification basis for the calculation of large-scale rice planting area, yield and other information.
In this paper, we propose a novel robust audio watermarking scheme in spectrum. Because most of audio spectrum coefficient value are around zero except for two sides, we propose to embed data by manipulating statistical mean of selected spectrum coefficients. Our experiment results have shown that the novel audio watermarking scheme in spectrum domain can achieve imperceptibleness and robustness
Abstract With the rapid iteration of computer digital tech, the processing level of remote sensing image has made outstanding achievements and progress, which greatly improves the processing level and ability of remote sensing image. Therefore, the research on remote sensing image processing assisted by computer digital tech has important practical value. Based on this, this paper first analyzes the digital characteristics and properties of remote sensing image, then studies the remote sensing image processing process based on computer digital tech, and finally gives the development trend of remote sensing image processing based on computer digital tech.
Amplitude versus offset (AVO) interpretation can be facilitated by cross‐plot of AVO intercept , gradient , and curvature .It is theoretically possible to obtain the all attributes exactly. However, the method had a little success in practice because the high order coefficient C dominates the process as the critical angle is approached and has a poor S/N ratio (Swan,1993).An alterative approach, which uses to substitute and its high‐order terms can make the reflection coefficients be controlled by the three new attributes simultaneously no matter in small angles, intermediate angles, or large angles (Sun, 2004a; 2004b).In this paper we investigate the rationality of the three attributes AVO as an indicator of the gas saturation in a reservoir. First, we discuss the relationships between the modified attributes and the characters of cross‐plots for Castagna and Smith's (1994) worldwide examples. Consequently, by analyzing the 2D & 3D cross‐plots of inverted AVO attributes for a real well log data, we highlight the advantages in robust three parameters inversion as well as in construction multiple cross‐plots. The result also shows that the presented method would be more stable and less ambiguous in both fluid content detection and lithology discrimination than the traditional AVO cross‐plots.
with the development of high density seismic exploration, high efficient acquisition has been the necessary seismic methods. Recently years, methods such as slide-sweep, DSSS have made great progress. Based on the research of high efficient acquisition methods and test results in Oman, BGP, we proposed the concept of blending acquisition and summarized preliminarily the characteristics of key parameters of blending data, the differences between blending from conventional and slide-sweep acquisition.
Based on the re‐expression of the three‐term AVO equation for the PP wave reflection coefficient given by Aki and Richards (1980), two improved AVO formulas involving elastic parameters and their applications are presented in this paper. Unlike traditional AVO approximations, the new expressions can be used not only to extract new attributes which are sensitive to lithology and fluids, but also to invert the elastic‐parameter reflectivity volumes, such as the Lamé constant, the shear modulus, as well as bulk density simultaneously. Furthermore, multi‐attributes AVO analysis and integrated oil/gas prediction is favored because there is no loss in accuracy for the new equations. The results of the rock physics analysis and applications to real data show that the new method is more stable and less ambiguous than the conventional methods, which are currently used to discriminate reservoir sands from other lithologies and between low‐ and full‐saturation of hydrocarbons. In addition, the inversion results on synthetic data indicate that the modified approximations can provide more reliable results in layered parameters, like P‐ impedance, S‐ impedance, and LMR (Lambda‐Mu‐Rho).
In this paper, a digital image blind watermarking algorithm is proposed based on neighboring relation in wavelet transform domain which can detect watermarking without using the original image. The original image is transformed by wavelet transforming, and the watermark is embedded in the selected detail subband according to neighboring symbol's average value. The experiment shows that this method is of better invisibility and robustness.
In this paper, a digital image watermarking based on Arnold transform and pseudo-random permutation is proposed. The digital watermark which is a binary image is first transformed into a worthless image using pseudo-random permutation and a secret key is used to express the initial value. The image then is transformed by using Arnold transform and an another secret key is used to control the scrambling numbers. The secret image is embedded into the DCT coefficients of the original image. Experimental results show that this algorithm can generate a digital watermark with the high security.
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