SVM method for predicting the thickness of sandstone

The Support Vector Machine （SVM） method can be used to set up a nonlinear function prediction model. It is based on the small sample learning theory. The kernel function can be constructed automatically based on the actual sample data by using the SVM method. As a result, the function not only gets a higher fit precision but is also better generalized. The frequency spectrum and seismic waveform are related by Fourier transform, so they are two different forms of the same physical phenomenon. The variety of waveform character reflects stratigraphic differences and frequency spectrum differences reflect the variation of lithology, fluid composition, and formation thickness. It directly predicts sandstone thickness using the seismic waveform. This not only fully utilizes the seismic information but also greatly increases the accuracy of the prediction. Model examples and actual applications show the applicability of this method.

坚硬特厚煤层综采放顶煤液压支架研制

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Conventional triaxial compression on hollow cylinders of sandstone with various fillings: Relationship of surrounding rock with support

The interaction of surrounding rock with a support system in deep underground tunnels has attracted extensive interest from researchers.However,the effect of high axial stress on tunnel stability has not been fully considered.In this study,compression tests with and without confining pressure were conducted on solid specimens and hollow cylinder specimens filled with aluminium,lead,and polymethyl methacrylate(PMMA)to investigate the strength,deformation and failure characteristics of circular roadways subjected to high axial stress.The influence of the three-dimensional stress on the surrounding rock supported with different stiffness was studied.The results indicate that the strength and peak strain of hollow cylinders filled with PMMA are higher than those of hollow cylinders filled with aluminium or lead,indicating that flexible retaining is beneficial for roadway stability.The results obtained in this paper can contribute to better understanding the support failure of a buried roadway subjected to high axial stress and thus to analyzing and evaluating roadway stability.

Sedimentary microfacies of the H8 member in the Su14 3D seismic test area

The distribution of sedimentary microfacies in the eighth member of the Shihezi formation（the H8 member） in the Sul4 3D seismic test area was investigated.A Support Vector Machine（SVM） model was introduced for the first time as a way of predicting sandstone thickness in the study area.The model was constructed by analysis and optimization of measured seismic attributes.The distribution of the sedimentary microfacies in the study area was determined from predicted sandstone thickness and an analysis of sedimentary characteristics of the area.The results indicate that sandstone thickness predictions in the study area using an SVM method are good.The distribution of the sedimentary microfacies in the study area has been depicted at a fine scale.

Pulmonary nodules: optimal slice thickness of CT in revealing bronchial imageology

Objective： The aim of our study was to determine an optimal slice thickness that was efficient in revealing bronchial imageology of pulmonary nodules （PNs） on multi-slice spiral computed tomography （MSCT） images preliminarily. Methods： Fifty-four patients with 62 PNs （diameter 〈 3 cm） underwent multidetector-row computed tomography of the chest in a single-breath-hold technique. The raw data were acquired with a collimation of 0.625 mm. Three sets of contiguous im- ages were reconstructed with 1-, 2-, and 5-mm slice thickness, respectively. Bronchial imageology of SPNs on the CT images presented in 1-, 2-, and 5-mm slice thickness was compared. Using the 1-mm sections as the gold standard, an optimal slice thickness in revealing bronchial imageology of PNs was determined. Results： Bronchial imageology of PNs on the CT images presented in 1 mm slice thickness involved 85 bronchi （35 second-fourth generation bronchi; 50 fifth-eighth generation bronchi）. Bronchial imageology on 2-mm-thick sections was as same as that on I-mm-thick sections in 34 second- fourth generation bronchi. No statistically significant difference in number of second- fourth generation bronchi with same bronchial imageology was found between that on 2-mm-thick images and I-mm-thick images （P = 0.836 〉 0.05）. Bronchial imageology on 5-mm-thick sections was as same as that on 1-mm-thick sections in 24 second-fourth generation bronchi. There was statistically significant difference in number of second-fourth generation bronchi with same bronchial imageology between that on 5-mm-thick images and 1-mm-thick images （P = 0.026 〈 0.05）. Bronchial imageology on 2-mm-thick sections was as same as that on 1-mm-thick sections in 38 fifth-eighth generation bronchi. There was statistically significant difference in number of fifth-eighth generation bronchi with same bronchial imageology between that on 2-mm-thick images and 1-mm- thick images （P = 0.029 〈 0.05）. Bronchial imageology on 5-mm-thick images was as same as that on I-mm-thick images in 31 fifth-eighth generation bronchi. There was statistically significant difference in number of fifth-eighth generation bronchi with same bronchial imageology between that on 5-mm-thick sections and I-mm-thick sections （P = 0.001 〈 0.05）. Conclusion： It is suggested that the use of 2-mm slice thickness is suitable in revealing second- fourth generation bronchi and the use of l-mm slice thickness is suitable in revealing fifth-eighth generation bronchi.

Depillaring of total thickness of a thick coal seam in single lift using cable bolts：A case study

Explaining fundamentals of application of cable bolting for a thick seam depillaring,this paper summarizes the results of field studies conducted during adoption of this approach in more than fifteen panels of Madhusudanpur 7 pit and incline mine.Nearly 7.0 m thick Kajora top coal seam of this mine is developed on pillars along the floor horizon to an average height of 3.0 m,leaving a coal band of around 4.0 m along the roof.Analysis of procured core samples showed that roof strata are easily caveable with a caveability index value of around 2000 only.Easily caveable overlying strata and shallow depth of cover alleviated most of the expected strata mechanics problems of the thick seam mining.However,extraction of total thickness at shallow cover caused differential-subsidence and cracks on the surface.These manifestations were immediately tackled to avoid creation of a breathing path for spontaneous heating in the extracted area.

A method to calculate displacement factors using SVM

In order to improve the precision of mining subsidence prediction, a mathematical model using Support Vector Machine （SVM） was established to calculate the displacement factor. The study is based on a comprehensive analysis of factors affecting the displacement factor, such as mechanical properties of the cover rock, the ratio of mining depth to seam thickness, dip angle of the coal seam and the thickness of loose layer. Data of 63 typical observation stations were used as a training and testing sample set. A SVM regression model of the displacement factor and the factors affecting it was established with a kernel function, an insensitive loss factor and a properly selected penalty factor. Given an accurate calculation algorithm for testing and analysis, the results show that an SVM regression model can calcu- late displacement factor precisely and reliable precision can be obtained which meets engineering requirements. The experimental results show that the method to calculation of the displacement factor, based on the SVM method, is feasible. The many factors affecting the displacement factor can be consid- ered with this method. The research provides an efficient and accurate approach for the calculation of displacement in mining subsidence orediction.