The influence of some blasting techniques on the probability of ignition of firedamp by permissible explosives

The ignition of firedamp by permissible explosives is assessed by means of gallery testing conducted by the Bruceton up-and-down method. Six test series were made in order to analyze the influence of several blasting practices in long-holes coal blasting, namely: use of slotted PVC pipes, detonating cord, salt cartridges and double (top and bottom) initiation. The parameters of the distributions of the probability of ignition are determined by the maximum likelihood method; normal, logistic, lognormal and Weibull distributions have been used. Confidence bands for the probability points are obtained both from the asymptotic standard errors of the parameters and by a bootstrap-like technique. The four distributions used give similar results in a rather ample probability range; discrepancies in the probability points are within 2% and in the confidence limits within 10% in a range of probability [0.1, 0.9] in most of the cases. The use of detonating cord is found to affect significantly the probability of ignition; the double initiation does also have an influence though not statistically significant at a 95% level; the use of salt cartridges, in the amount tested, has little effect in the ignition probability; the use of PVC pipe shows no effect.     

改进偏最小二乘回归在电力负荷预测中的应用

多元回归分析是中长期电力负荷预测中的一个重要方法,其中偏最小二乘法因为可以有效解决样本数据偏少以及自变量多重线性的问题而得到采用。探讨了通过Bootstrap方法给偏最小二乘法筛选自变量后进行负荷分析预测的可行性,将计算结果与一般偏最小二乘法及经变量筛选的逐步回归法进行比较。算例表明,应用Bootstrap方法进行参数检验的偏最小二乘方法在变量关系的描述上更简明准确,同时提高了预测精度,具有一定的实用性。     

极小子样试验的虚拟增广样本评估方法

提出一种针对极小子样试验的虚拟增广样本评估方法。在工程实际中，对于成本昂贵的大型复杂结构体系或机构系统，往往只能做试件样本量为1或2的极小子样试验。在这种情况下，先根据极小子样试验的试验样本值虚拟增广样本，即把样本量从n=1虚拟增广至n=13，然后根据增广样本构造经验累积分布函数并对其进行修正，最后应用Bootstrap方法对增广样本进行评估，得到未知参数的估计。文中采用一个实例验证了所提出方法的实用性。     

小样本下装备平均维修时间验前分布确定方法研究

针对装备维修性试验数据小样本的实际,选取Bayes方法,对小样本下平均修复时间（mean time to repair,MTTR）验前分布的求取方法进行改进。依据不同的样本量,分别采用Bootstrap方法、最大熵法、Bootstrap与最大熵结合法及极小子样的虚拟增广样本法确定总体的验前分布,重点对其原理和计算过程进行说明,并利用实例对每种验前分布确定方法进行了验证分析,最后总结比较了各种方法的优缺点,为其实际使用提供了参考。     

基于Bootstrap方法的实物期权定价

在进行实物期权定价时,引入了统计学方法Bootstrap,确定期权的波动率。利用非参数法得出实物期权的价值及最佳执行期权时间,从而实现实物期权的定价。     

基于Bootstrap滤波的非线性系统的识别

Bootstrap滤波是一种基于贝叶斯状态估计和蒙特卡罗方法的新的海波方法，相对于经典的卡尔曼滤波而言，它不受状态方程须为线性以及状态与噪声须是高斯分布的限制，具有很强的适应性。对贝叶斯估计及Bootstrap滤波方法在非线性系统识别中的应用进行了分析与数值模拟，计算结果表明了该方法的有效性和实用性。     

基于自助法的水文频率区间估计

介绍了采用自助法估计水文频率区间的原理与方法,对经验分位数自助法、纠偏自助法、正态分布近似自助法、学生分布近似自助法等进行了简要的描述,并将纠偏加速自助法引入到水文频率区间估计中.通过统计试验,将自助法与水文频率分析区间估计的常用方法,包括保证修正值系数B方法、Stedinger方法等进行比较研究.试验结果表明:在估计水文频率的上界值时,纠偏加速自助法效率最高,为水文频率区间估计提供了新的思路.     

对HP ThinClient上Linux的启动过程进行速度优化

通过对HP ThinElient上的Linux系统启动过程的分析，针对速度优化问题进行了探讨。首先，按启动本身的顺序较详细地给出了启动过程的描述并指出了影响启动速度的主要因素；然后，分阶段提出了进行速度优化的建议．并给出一个实际测试结果。     

Bootstrap Inference for Garch Models by the Least Absolute Deviation Estimation

This article considers the generalized bootstrap method to approximate the least absolute deviation estimation and portmanteau test for generalized autoregressive conditional heteroskedastic models. The generalized bootstrap approach is easy-to-implement, and includes many bootstrap methods as special cases, such as Efron's bootstrap, Bayesian bootstrap, and random-weighting bootstrap. The proposed bootstrap procedure is shown to be asymptotically valid for both estimation and test. The finite-sample performance is assessed by simulation studies, and its usefulness is illustrated by a real application to the Hang Seng Index.     

Bootstrap current fraction scaling for a tokamak reactor design study

We have derived new bootstrap current fraction scalings for systems codes by solving the Hirshman–Sigmar model, which is valid for arbitrary aspect ratios and collision conditions. The bootstrap current density calculation module in the ACCOME code was used with the matrix inversion method without the large aspect ratio assumption. Nine self-consistent MHD equilibria, which cover conventional, advanced and spherical tokamaks with normal or reversed shear, were constructed using numerical calculations in order to compare the bootstrap current fraction values with those of the new model and all six existing models. The Wilson formula successfully predicted the bootstrap current fraction, but it requires current density profile index for the calculation. The new scaling formulas and IPDG accurately estimated the bootstrap current fraction for the normal and weakly reversed shear tokamaks, regardless of the aspect ratio. However, none of the existing models except the Wilson formula can accurately estimate the bootstrap current fraction for the reversed shear tokamaks, which is promising for the advanced tokamak operation mode.