Due to the existence of thermal offsets,global solar irradiances measured by pyranometers are smaller than actual values,and errors are larger in the daytime.Until now,there is no universally-recognized correction met...Due to the existence of thermal offsets,global solar irradiances measured by pyranometers are smaller than actual values,and errors are larger in the daytime.Until now,there is no universally-recognized correction method for thermal offset errors.Therefore,it is imperative to identify a convenient and effective correction method.Five correction methods were evaluated based on the data measured from a field experiment from 23 January to 15 November,2011.Results have shown:1) Temporal variation characteristics of thermal offsets in the four tested pyranometers are consistent.2) Among the five methods,non-dimensional quantity method is suggested for use to correct thermal offsets,because it is convenient and no modification of instruments is required.If collocated net longwave radiation and wind speed data are available and their uncertainties are small,the historical solar radiation datasets can also be corrected.And correction effects by the method are better.展开更多
In this paper, rock mass is regarded as anisotropic clastic units and the partial differential equation of subsidence has been testified. The solution about homogeneous anisotropy has been obtained. The existence of i...In this paper, rock mass is regarded as anisotropic clastic units and the partial differential equation of subsidence has been testified. The solution about homogeneous anisotropy has been obtained. The existence of inflection point offset in subsidence formula has been proved. Lastly, the relevant influence factors about the offset of inflection point have been simply discussed.展开更多
The method and principle of common offset seismic surveys as well as the field data gathering and processing technique were introduced briefly. Through two urban active fault survey examples in Fuzhou and Shenyang, th...The method and principle of common offset seismic surveys as well as the field data gathering and processing technique were introduced briefly. Through two urban active fault survey examples in Fuzhou and Shenyang, the efficiency and limitation of using the common offset seismic reflection technique to carry out urban active fault surveys were probed. The results show that this technique has the properties of high resolving power, better reconstruction of subsurface structures, and real-time analyzing and interpretation of investigation results on site. This method can be used to quickly locate objects under investigation accurately in the areas with thinner Quaternary overburdens and strong bedrock interface fluctuations.展开更多
The attenuation factor or quality factor(Q-factor or Q) has been used to measure the energy attenuation of seismic waves propagating in underground media. Many methods are used to estimate the Q-factor. We propose a m...The attenuation factor or quality factor(Q-factor or Q) has been used to measure the energy attenuation of seismic waves propagating in underground media. Many methods are used to estimate the Q-factor. We propose a method to calculate the Q-factor based on the prestack Q-factor inversion and the generalized S-transform. The proposed method specifies a standard primary wavelet and calculates the cumulative Q-factors; then, it finds the interlaminar Q-factors using the relation between Q and offset(QVO) and the Dix formula. The proposed method is alternative to methods that calculate interlaminar Q-factors after horizon picking. Because the frequency spectrum of each horizon can be extracted continuously on a 2D time–frequency spectrum, the method is called the continuous spectral ratio slope(CSRS) method. Compared with the other Q-inversion methods, the method offers nearly effortless computations and stability, and has mathematical and physical significance. We use numerical modeling to verify the feasibility of the method and apply it to real data from an oilfield in Ahdeb, Iraq. The results suggest that the resolution and spatial stability of the Q-profile are optimal and contain abundant interlaminar information that is extremely helpful in making lithology and fluid predictions.展开更多
Principles of polynomial fitting zero offset profile are introduced, and a new polynomial fitting method, tbe time-amplitude dual fitting method, is developed. The method can be used to purify seismic waves and suppre...Principles of polynomial fitting zero offset profile are introduced, and a new polynomial fitting method, tbe time-amplitude dual fitting method, is developed. The method can be used to purify seismic waves and suppress multiples. The effect of suppressing multiples is compared with other multiple suppression methods.展开更多
基金National Science Foundation of China for Young Scholars(40905071)National Natural Science Foundation of China for General Program(41275114)
文摘Due to the existence of thermal offsets,global solar irradiances measured by pyranometers are smaller than actual values,and errors are larger in the daytime.Until now,there is no universally-recognized correction method for thermal offset errors.Therefore,it is imperative to identify a convenient and effective correction method.Five correction methods were evaluated based on the data measured from a field experiment from 23 January to 15 November,2011.Results have shown:1) Temporal variation characteristics of thermal offsets in the four tested pyranometers are consistent.2) Among the five methods,non-dimensional quantity method is suggested for use to correct thermal offsets,because it is convenient and no modification of instruments is required.If collocated net longwave radiation and wind speed data are available and their uncertainties are small,the historical solar radiation datasets can also be corrected.And correction effects by the method are better.
文摘In this paper, rock mass is regarded as anisotropic clastic units and the partial differential equation of subsidence has been testified. The solution about homogeneous anisotropy has been obtained. The existence of inflection point offset in subsidence formula has been proved. Lastly, the relevant influence factors about the offset of inflection point have been simply discussed.
基金This research was supported by the project of "Experimental Prospecting of Active Fault in Urban Area"of the National Development and Reform Commission of China (Grant No.20041138)
文摘The method and principle of common offset seismic surveys as well as the field data gathering and processing technique were introduced briefly. Through two urban active fault survey examples in Fuzhou and Shenyang, the efficiency and limitation of using the common offset seismic reflection technique to carry out urban active fault surveys were probed. The results show that this technique has the properties of high resolving power, better reconstruction of subsurface structures, and real-time analyzing and interpretation of investigation results on site. This method can be used to quickly locate objects under investigation accurately in the areas with thinner Quaternary overburdens and strong bedrock interface fluctuations.
基金supported by The National Key Research and Development Program Plane(No.2017YFC0601505)National Natural Science Foundation(No.41672325)Science&Technology Department of Sichuan Province Technology Project(No.2017GZ0393)
文摘The attenuation factor or quality factor(Q-factor or Q) has been used to measure the energy attenuation of seismic waves propagating in underground media. Many methods are used to estimate the Q-factor. We propose a method to calculate the Q-factor based on the prestack Q-factor inversion and the generalized S-transform. The proposed method specifies a standard primary wavelet and calculates the cumulative Q-factors; then, it finds the interlaminar Q-factors using the relation between Q and offset(QVO) and the Dix formula. The proposed method is alternative to methods that calculate interlaminar Q-factors after horizon picking. Because the frequency spectrum of each horizon can be extracted continuously on a 2D time–frequency spectrum, the method is called the continuous spectral ratio slope(CSRS) method. Compared with the other Q-inversion methods, the method offers nearly effortless computations and stability, and has mathematical and physical significance. We use numerical modeling to verify the feasibility of the method and apply it to real data from an oilfield in Ahdeb, Iraq. The results suggest that the resolution and spatial stability of the Q-profile are optimal and contain abundant interlaminar information that is extremely helpful in making lithology and fluid predictions.
文摘Principles of polynomial fitting zero offset profile are introduced, and a new polynomial fitting method, tbe time-amplitude dual fitting method, is developed. The method can be used to purify seismic waves and suppress multiples. The effect of suppressing multiples is compared with other multiple suppression methods.
