Failure probability analysis of coal crushing induced by uncertainty of influential parameters under condition of in-situ reservoir

The uncertainties of some key influence factors on coal crushing,such as rock strength,pore pressure and magnitude and orientation of three principal stresses,can lead to the uncertainty of coal crushing and make it very difficult to predict coal crushing under the condition of in-situ reservoir.To account for the uncertainty involved in coal crushing,a deterministic prediction model of coal crushing under the condition of in-situ reservoir was established based on Hoek-Brown criterion.Through this model,key influence factors on coal crushing were selected as random variables and the corresponding probability density functions were determined by combining experiment data and Latin Hypercube method.Then,to analyze the uncertainty of coal crushing,the firstorder second-moment method and the presented model were combined to address the failure probability involved in coal crushing analysis.Using the presented method,the failure probabilities of coal crushing were analyzed for WS5-5 well in Ningwu basin,China,and the relations between failure probability and the influence factors were furthermore discussed.The results show that the failure probabilities of WS5-5 CBM well vary from 0.6 to 1.0; moreover,for the coal seam section at depth of 784.3-785 m,the failure probabilities are equal to 1,which fit well with experiment results; the failure probability of coal crushing presents nonlinear growth relationships with the increase of principal stress difference and the decrease of uniaxial compressive strength.

Consistent Criteria for checking Hypotheses

This paper we study a consistent criterion for checking Hypotheses. Given definition of consistent criterion for checking hypotheses for family probability measures which were defined by Z. Zerakidze （see 5）. We prove the necessary and sufficient conditions are obtained for the existence of consistent criteria of hypotheses. For example we clearly build of a consistent criteria for checking hypotheses.

飞行目标脉冲激光测距的回光稳定性

基于脉冲激光测距原理,推导了飞行目标激光测距回光功率的一般方程。基于目标探测跟踪系统的瞄准误差理论,结合测距方程建立了系统准测概率的计算模型。利用Matlab软件仿真分析了激光发散角、系统跟踪精度、目标尺度、探测距离及系统接收口径对回光稳定性的影响。设计了一个飞行目标脉冲激光测距系统,并根据理论分析结果确定了该系统参数,搭建了实验平台。通过对无人机靶板目标的跟踪测距实验,验证了系统的探测性能。通过对比不同大小靶板目标的准测概率与理论推算结果,验证了该模型的有效性。