Improved phase estimation based on complete bispectrum and modified group delay

In this paper, a new method for extracting the system phase from the bispectrum of the system output has been proposed. This is based on the complete bispectral data computed in the frequency domain and modified group delay. The frequency domain bispectrum computation improves the frequency resolution and the modified group delay reduces the variance preserving the frequency resolution. The use of full bispectral data also reduces the variance as it is used for averaging. For the proposed method at a signal to noise ratio of 5dB, the reduction in root mean square error is in the range of 1.5–7 times over the other methods considered.     

考虑群锚效应的植筋群受拉承载力分析

在分析比较国内外锚栓受拉计算方法和影响因素等研究成果的基础上,从两组不同埋深的植筋群受拉试验入手,研究了植筋群的承载力、破坏形式、内力变化等性能,得出一些有益的结论.     

A new knowledge reduction algorithm for information system

The discernible Boolean matrix of information system is defined. The model of attribute reduction in the form of linear logical equations is established. The necessary and sufficient condition for determining whether the attribute is absolutely necessary, relatively necessary and absolutely superfluous is given. Finally, an elementary knowledge reduction algorithm is proposed.     

考虑施工顺序及遮栏效应的静压群桩挤土位移场研究

基于应变路径法及源汇法理论,建立了已存在桩情况下单桩挤土位移场。在此基础上,结合拉格朗日插值函数推导出了考虑施工顺序及遮栏效应的群桩挤土位移场的解析解。该解较各桩的简单叠加更符合工程实际情况,而且能够简化为不考虑施工顺序的静压群桩挤土位移场的解答。利用得到的解析解对群桩产生的挤土位移场进行了分析,结果表明:与忽略施工顺序及遮栏效应的群桩挤土位移场相比,考虑施工顺序及遮栏效应的迎桩面挤土位移较大,而背桩面的挤土位移较小。     

A two-stage empirical Bayes method for identifying differentially expressed genes

Due to the high dimensionality of microarray gene expression data and complicated correlations in gene expression levels, statistical methods for analyzing these data often are computationally intensive, requiring special expertise for their implementation. Biologists without such expertise will benefit from a computationally efficient and easy-to-implement analytic method. In this article, we develop such a method: a two-stage empirical Bayes method for identifying differentially expressed genes. We use a special technique to reduce the dimension of the parameter space in the preliminary stage, and construct a Bayesian model in the second stage. The computation of our method is efficient and requires little calibration for real microarray gene expression data. Specifically, we employ statistical tools, including the empirical Bayes estimation and a distribution approximation approach, to speed up computation and at the same time to preserve precision. We develop a score for evaluating the magnitude of the overall differential gene expression levels based on our Bayesian model, and declare differential expression according to the posterior probabilities that their scores exceed some threshold value. The number of declarations is determined by a false discovery rate procedure.     

费用非对称通信网络上的群播路由算法

文中考虑了费用非对称通信网络上的群播路由问题,提出了一种接近最小成本的启发式算法--NEW-GM算法.该算法以FMPH(Fast Minimum Path Cost HouriStic)为基础,可以有效的降低成本.数值实验表明:这种算法是有效的,且所获得问题解的总费用几乎总是小于或等于由GTM算法所获得的解的总费用.NEW-GM算法的时间复杂度与GTM算法的相同,为O(p3n2).     

混编集成末端防空群指挥跨度研究

针对确定指挥跨度缺少定量依据的问题,研究基于信息化指挥手段的混编集成防空群指挥跨度定量分析 方法。定性分析影响混编集成指挥跨度的指挥主体、指挥对象及指挥手段等因素;在管理学格拉丘纳斯公式的基础 上,引入信息化效率因子、指挥难度指数和协同难度指数修正该公式,计算混编集成情况下指挥控制工作关系数, 衡量指挥控制工作的复杂程度,与传统编成经验值相比较,并以首都地区某末端防空群为例进行计算。结果表明： 混编集成指挥跨度为6,可为确定多型防空兵器混编集成指挥跨度提供一定的理论依据。     

蛋白类缓凝剂对建筑石膏的适应性

分析比较了4种分子结构相近的蛋白类缓凝剂对脱硫建筑石膏(FGD)和磷建筑石膏(PG)的缓凝效果.结果表明:具有不同酰胺键类型的蛋白类缓凝剂,其缓凝度受建筑石膏类型影响,且随建筑石膏pH值的增加而增大;当蛋白类缓凝剂的酰胺基团主要为仲酰胺时,其缓凝度随着H_2PO_4~-含量的增加而降低,当蛋白类缓凝剂的酰胺基团主要为伯酰胺时,其缓凝剂不易受H_2PO_4~-的影响;用于FGD的蛋白类缓凝剂宜选用仲酰胺为主的酰胺基团,用于PG的蛋白类缓凝剂宜选用伯酰胺为主的酰胺基团.     

Physical modeling of behaviors of cast-in-place concrete piled raft compared to free-standing pile group in sand

Similar to free-standing pile groups, piled raft foundations are conventionally designed in which the piles carry the total load of structure and the raft bearing capacity is not taken into account. Numerous studies indicated that this method is too conservative. Only when the pile cap is elevated from the ground level, the raft bearing contribution can be neglected. In a piled raft foundation, pile–soil–raft interaction is complicated. Although several numerical studies have been carried out to analyze the behaviors of piled raft foundations, very few experimental studies are reported in the literature. The available laboratory studies mainly focused on steel piles. The present study aims to compare the behaviors of piled raft foundations with free-standing pile groups in sand, using laboratory physical models. Cast-in-place concrete piles and concrete raft are used for the tests. The tests are conducted on single pile, single pile in pile group, unpiled raft, free-standing pile group and piled raft foundation. We examine the effects of the number of piles, the pile installation method and the interaction between different components of foundation. The results indicate that the ultimate bearing capacity of the piled raft foundation is considerably higher than that of the free-standing pile group with the same number of piles. With installation of the single pile in the group, the pile bearing capacity and stiffness increase. Installation of the piles beneath the raft decreases the bearing capacity of the raft. When the raft bearing capacity is not included in the design process, the allowable bearing capacity of the piled raft is underestimated by more than 200%. This deviation intensifies with increasing spacing of the piles.