Prediction method for risks of coal and gas outbursts based on spatial chaos theory using gas desorption index of drill cuttings

Based on the evolution of geological dynamics and spatial chaos theory, we proposed the advanced prediction an advanced prediction method of a gas desorption index of drill cuttings to predict coal and gas outbursts. We investigated and verified the prediction method by a spatial series data of a gas desorption index of drill cuttings obtained from the 113112 coal roadway at the Shitai Mine. Our experimental results show that the spatial distribution of the gas desorption index of drill cuttings has some chaotic charac- teristics, which implies that the risk of coal and gas outbursts can be predicted by spatial chaos theory. We also found that a proper amount of sample data needs to be chosen in order to ensure the accuracy and practical maneuverability of prediction. The relative prediction error is small when the prediction pace is chosen carefully. In our experiments, it turned out that the optimum number of sample points is 80 and the optimum prediction pace 30. The corresponding advanced prediction pace basically meets the requirements of engineering applications.

Optimization approach of background value and initial item for improving prediction precision of GM(1,1) model

A combination method of optimization of the back-ground value and optimization of the initial item is proposed. The sequences of the unbiased exponential distribution are simulated and predicted through the optimization of the background value in grey differential equations. The principle of the new information priority in the grey system theory and the rationality of the initial item in the original GM（1,1） model are ful y expressed through the improvement of the initial item in the proposed time response function. A numerical example is employed to il ustrate that the proposed method is able to simulate and predict sequences of raw data with the unbiased exponential distribution and has better simulation performance and prediction precision than the original GM（1,1） model relatively.

Real-time 3-D space numerical shake prediction for earthquake early warning

In earthquake early warning systems, real-time shake prediction through wave propagation simulation is a promising approach. Compared with traditional methods, it does not suffer from the inaccurate estimation of source parameters. For computation efficiency, wave direction is assumed to propagate on the 2-D surface of the earth in these methods. In fact, since the seismic wave propagates in the 3-D sphere of the earth, the 2-D space modeling of wave direction results in inaccurate wave estimation. In this paper, we propose a 3-D space numerical shake pre- diction method, which simulates the wave propagation in 3-D space using radiative transfer theory, and incorporate data assimilation technique to estimate the distribution of wave energy. 2011 Tohoku earthquake is studied as an example to show the validity of the proposed model. 2-D space model and 3-D space model are compared in this article, and the prediction results show that numerical shake prediction based on 3-D space model can estimate the real-time ground motion precisely, and overprediction is alleviated when using 3-D space model.

DFT Predictions on Structures and Stabilities of Eleven-vertex nido- and closo-Heteroboranes

Based on the octadecahedron of eleven-vertex closo-borane, the eleven-vertex closo-heteroborane was suggested with nonmetallic atoms instead of the different nonequivalent boron, and the stabilities were predicted at G96PW91/6-31＋G（3d,2p） level. The small heteroatoms, C, N, O, preferentially occupy vertex 2 with the absolutely lowest relative energy to form the high stabilization closo-heteroboranes. They cap four-membered rings to satisfy the geometrical demand of short B--Z bonds. The electron attractions from the vicinal boron atoms make the frameworks shrink. Differently, Si and Ge preferentially substitute for boron at vertex 1 with six tight B--Z bonds and form stabilized molecules. P, As, S, and Se tend to occupy vertex 4 and the optimized structures belong to the nido configura- tions. In contrast to high electronegative heteroatoms, S and Se transfer less negative charges to framework and the electropositive heteroatoms, Si and Ge transfer more negative charges to framework to form the delocalization structures. The HOMO-LUMO gaps show that most of predicted clusters possess chemical stabilities. The substitutions of heteroatoms for boron atoms in eleven-vertex closo-heteroboranes are consistent with the topological charge stabilization rule proposed by Gimarc.

Real-time numerical shake prediction and updating for earthquake early warning

Ground motion prediction is important for earthquake early warning systems, because the region＇s peak ground motion indicates the potential disaster. In order to predict the peak ground motion quickly and pre- cisely with limited station wave records, we propose a real- time numerical shake prediction and updating method. Our method first predicts the ground motion based on the ground motion prediction equation after P waves detection of several stations, denoted as the initial prediction. In order to correct the prediction error of the initial prediction, an updating scheme based on real-time simulation of wave propagation is designed. Data assimilation technique is incorporated to predict the distribution of seismic wave energy precisely. Radiative transfer theory and Monte Carlo simulation are used for modeling wave propagation in 2-D space, and the peak ground motion is calculated as quickly as possible. Our method has potential to predict shakemap, making the potential disaster be predicted before the real disaster happens. 2008 Ms8.0 Wenchuan earthquake is studied as an example to show the validity of the proposed method.

Generation and Application of A Standardized Load-Time History to Tubular T-joints in Offshore Platforms

Marine structures are mostly made of metals and always experience complex random loading during their service periods. The fatigue crack growth behaviors of metal materials have been proved from laboratory tests to be sensitive to the loading sequence encountered. In order to take account of the loading sequence effect, fatigue life prediction should be based on fatigue crack propagation（FCP） theory rather than the currently used cumulative fatigue damage（CFD） theory. A unified fatigue life prediction（UFLP） method for marine structures has been proposed by the authors＇ group. In order to apply the UFLP method for newly designed structures, authorities such as the classification societies should provide a standardized load-time history（SLH） such as the TWIST and FALSTAFF sequences for transport and fighter aircraft. This paper mainly aims at proposing a procedure to generate the SLHs for marine structures based on a short-term loading sample and to provide an illustration on how to use the presented SLH to a typical tubular T-joint in an offshore platform based on the UFLP method.

A method based on diffraction theory for predicting 3D focusing performance of compound refractive X-ray lenses

A method based on the diffraction theory for estimating the three-dimensional (3D) focusing performance of the compound refractive X-ray lenses is presented in this paper. As a special application, the 3D X-ray intensity distribution near the focus is derived for a plano-concave compound refractive X-ray lens. Moreover, the computer codes are developed and some results of 3D focusing performance for a compound refractive X-ray lens with Si material are shown and discussed.

Study on Formation Mechanisms of Heavy Rainfall Within the Meiyu Along the Mid-Lower Yangtze River and Theories and Methods of Their Detection and Prediction

As the project of National Key Basic Research Development Program： Research on Formation Mechanisms and Predictive Theories of Major Weather Disasters in China has been fulfilled by 5-yr efforts of Chinese scientists, achieving results of great significance are as follows： 1） development of multi-scale physical models for Meiyu frontal heavy rainfall based on a range of real-time observations; 2） construction of synoptic models for such heavy rainfall; 3） the Meiyu front found to consist of multi-scale systems that represent a subtropical front, which shears structural features of an extratropical front and ITCZ, displaying sometimes a bi-front feature in the mid-lower Yangtze Basin （MLYB）. The positive feedback between pre-frontal wet physical processes and over-front strong convective activities as well as interactions among multi-scale systems of the Meiyu front act as the important mechanism for the maintenance and development of the Meiyu front; 4） proposal of theories and methods for quantitative retrieval of multiple mesoscale torrential rains from satellite remote sensings, leading to a line of products; 5） investigation of applicable theories and techniques for retrieving the heavy rainfall system＇s 3D structure from dual-Doppler synchronous detectings; and 6） development of a system for meso heavy rainfall numerical prediction models with a 3D variational data assimilation scheme included, a tool that played an active role in flood combating and relief activities over the Huaihe River Basin （HRB） in 2003.