不同压实矸石充填体置换``三下'煤柱的岩层移动规律

为了分析不同压实矸石的充填体置换``三下'煤柱所引起的岩层移动及稳定性等问题, 采用弹簧原理和弹塑性理论分析了上覆岩层和矸石充填支撑体的压缩机理, 并推导了矸石充 填体的初期压缩量; 根据充填体的压实原理、岩层力学及相关理论, 推导了不同矸石充填体 压实度所对应的压缩值及等价采高的解析式; 结合工程实例, 采用理论计算和数值模拟方法 分析了不同矸石充填体置换煤柱所对应的上覆岩层移动规律. 结果表明, 随着充填体压实度 的减小, 二次岩层移动所引起的顶板下沉值和等价采高都是不断增大的, 而当孔隙比达到 0.55左右, 所得到的等价采高$H_{e}$增长速度更加灵敏, 并且最大侧向位移增加趋势明显 加快.     

多价态钼多酸配合物[Mo(Ⅳ)Mo2(Ⅴ)O7(Phen)]的晶体结构及性质

用水热法合成了一种新的多价钼多酸配合物[Mo(Ⅳ)Mo2(Ⅴ)O7(Phen)],并用X射线衍射、元素分析、红外光谱、热重-差热、荧光光谱和磁化率等对其进行了表征.X射线衍射分析表明,配合物晶体属于单斜晶系,P2(1)/c空间群,由十二员环和八员环构成二维网状结构.配合物中强π-π堆积作用构筑成层状三维超分子,稳定了配...     

Synthesis of N-confused porphyrin derivatives with a substituted 3-C position

Active methylene compounds such as 5,5-dimethylcyclohexane-1,3-dione, cyclohexane-1,3-dione, 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one, 1,3-dimethyl-1H-pyrazol-5(4H)-one, and 3-methylisoxazol-5(4H)-one react with the 3-C position of N-confused porphyrin in THF for 5 min to afford a novel type of N-confused porphyrin derivatives in good yield without the need of any catalyst.     

Study on the interaction between salvianic acid A sodium and bovine serum albumin by spectroscopic methods

The interaction between salvianic acid A sodium (SAS) and bovine serum albumin (BSA) was investigated using fluorescence and ultraviolet spectroscopy at different temperatures under imitated physiological conditions. The experimental results showed that the fluorescence of BSA was quenched by SAS through a static quenching procedure. The binding constants of SAS with BSA were 2.03, 1.17 and 0.71×10(5) L mol(-1) at 291, 298 and 305 K, respectively. Negative values of ΔG, ΔH, and ΔS indicate that the interaction between SAS and BSA is driven by hydrogen bonds and van der Waals forces. According to F?rster non-radiation energy transfer theory, the binding distance between BSA and SAS was calculated to be about 2.92 nm. The effect of SAS on the conformation of BSA was analyzed using synchronous fluorescence spectroscopy. In addition, the effect of some metal ions Cu(2+), Ca(2+), Mg(2+), and Zn(2+) on the binding constant between SAS and BSA was examined.     

Efficient algorithms for generating truncated multivariate normal distributions

Sampling from a truncated multivariate normal distribution (TMVND) constitutes the core computational module in fitting many statistical and econometric models. We propose two efficient methods, an iterative data augmentation (DA) algorithm and a non-iterative inverse Bayes formulae (IBF) sampler, to simulate TMVND and generalize them to multivariate normal distributions with linear inequality constraints. By creating a Bayesian incomplete-data structure, the posterior step of the DA algorithm directly generates random vector draws as opposed to single element draws, resulting obvious computational advantage and easy coding with common statistical software packages such as S-PLUS, MATLAB and GAUSS. Furthermore, the DA provides a ready structure for implementing a fast EM algorithm to identify the mode of TMVND, which has many potential applications in statistical inference of constrained parameter problems. In addition, utilizing this mode as an intermediate result, the IBF sampling provides a novel alternative to Gibbs sampling and eliminates problems with convergence and possible slow convergence due to the high correlation between components of a TMVND. The DA algorithm is applied to a linear regression model with constrained parameters and is illustrated with a published data set. Numerical comparisons show that the proposed DA algorithm and IBF sampler are more efficient than the Gibbs sampler and the accept-reject algorithm.     

The decision of prime and primary ideal

We give more efficient criteria to characterise prime ideal or primary ideal. Further, we obtain the necessary and sufficient conditions that an ideal is prime or primary in real field from the Gröbner bases directly.     

Multiple solutions of boundary‐value problems for impulsive differential equations

In this paper, we investigate the existence of multiple solutions to a second‐order Dirichlet boundary‐value problem with impulsive effects. The proof is based on critical point theorems. Copyright © 2011 John Wiley & Sons, Ltd.     

四次带参Ball曲线的形状分析

基于包络理论与拓扑映射的方法对四次带参Ball曲线进行了形状分析,得出了曲线上含有奇点,拐点和曲线为局部凸或全局凸的充分必要条件,这些条件完全由控制多边形和形状参数所决定;并进一步讨论了形状参数对形状分布图的影响及其对曲线形状的调节能力.研究表明,四次带参Ball曲线的形状调控能力要优于四次带参Bezier曲线.     

W-Gröbner basis and monomial ideals under polynomial composition

The notion of weakly relatively prime and W-Gröbner basis in K[x ₁, x ₂, …, x _n ] are given. The following results are obtained: for polynomials f ₁, f ₂, …, f _m , \(\{ f_1^{\lambda _1 } ,f_2^{\lambda _2 } ,...,f_m^{\lambda _m } \} \) is a Gröbner basis if and only if f ₁, f ₂, …, f _m are pairwise weakly relatively prime with λ ₁, λ ₂, …, λ _m arbitrary non-negative integers; polynomial composition by Θ = (θ ₁, θ ₂, …, θ _n ) commutes with monomial-Gröbner bases computation if and only if θ ₁, θ ₂, …, θ _m are pairwise weakly relatively prime.     

Periodic boundary value problems for second order functional differential equations

This paper deals with a periodic boundary value problem for a second order functional differential equation. We obtain the existence of extreme solutions under new concept of upper and lower solutions. Also, a mistake in a recent paper (Ding et al. in J. Math. Anal. Appl. 298:341–351, 2004) is corrected.