基于正交枚举法的大型裂缝建筑加固优化方法研究与仿真

以往对大型裂缝建筑的震害预测及抗震加固,通常分析加固薄弱建筑单元,或者加固成本最低化为目标,没有对裂缝建筑体的服务水平进行分析。提出了基于正交枚举法的大型裂缝建筑加固优优化方法,依据大型裂建筑体的功能要求和抗震特征,将单元抗震可靠度以及震后各裂缝建筑段压力作为限制规范,确保震后裂缝建筑系统压力总降幅度最低化,并将总体裂缝建筑体固化投入最小化当成数学模型的优化目标,采用建筑单元可靠度变量的离散性,塑造了大型裂缝建筑加固优化模型,利用正交枚举法进行简化计算,实现大型裂缝建筑的加固优化求解。实验结果说明,所提方法实现了裂缝建筑的固化优化,并且具有较高的可靠度。     

Poisson Growth Mixture Modeling of Intensive Longitudinal Data: An Application to Smoking Cessation Behavior

This article illustrates the relation between structural equation modeling (SEM) and canonical correlation analysis (CCA). The representation of CCA in SEM may provide some important interpretive information that is not available from conventional CCA, that is, statistical tests for the canonical function and index coefficients, and statistical tests for individual canonical functions. Hierarchically, the relation between the two analytic approaches suggests that SEM stands to be a more general analytic approach. For researchers interested in these techniques, an understanding of the interrelation among them can be helpful to our choice of analytic method.     

论一类特殊的Pythagoras数

设x,y,z是正整数.如果x2 y2=z2,则称(x,y,z)是一组Pythagoras数.运用初等方法证明了:恰有12组Pythagoras数(x,y,z)适合6(x y z)=xy.     

Burnside定理在组合计数问题中的应用

针对一类组合计数方面的实际问题,利用二面体群、正多面体的对称性群等群的相关知识给出确切的数学描述,并运用Burnside轨道计数定理有效地加以解决,突破了用枚举法解决此类问题的局限性．     

Testing Measurement Invariance Across Unobserved Groups: The Role of Covariates in Factor Mixture Modeling

Factor mixture modeling (FMM) has been increasingly used to investigate unobserved population heterogeneity. This study examined the issue of covariate effects with FMM in the context of measurement invariance testing. Specifically, the impact of excluding and misspecifying covariate effects on measurement invariance testing and class enumeration was investigated via Monte Carlo simulations. Data were generated based on FMM models with (1) a zero covariate effect, (2) a covariate effect on the latent class variable, and (3) covariate effects on both the latent class variable and the factor. For each population model, different analysis models that excluded or misspecified covariate effects were fitted. Results highlighted the importance of including proper covariates in measurement invariance testing and evidenced the utility of a model comparison approach in searching for the correct specification of covariate effects and the level of measurement invariance. This approach was demonstrated using an empirical data set. Implications for methodological and applied research are discussed.     

Identifying Unobserved Hazard Functions in Discrete-Time Survival Mixture Analysis

This Monte Carlo simulation adds to the growing body of enumeration index performance research in continuous response variable mixture models by addressing the issue of the performance of these indexes in discrete-time survival mixture analysis (DTSMA) models. Results showed that although all enumeration indexes performed very well in identifying a homogeneous DTSMA model (i.e., k = 1 hazard function in the sample data), the findings also showed that the enumeration indexes performed poorly in identifying the correct number of unobserved hazard functions present in a heterogeneous (i.e., k = 3) DTSMA model. More important, the performance of the enumeration indexes for the heterogeneous DTSMA models did not improve as the sample size, the effect of time-invariant covariates, or adjacent hazard function separation distance increased, which is inconsistent with some previous Monte Carlo simulation results. The limitations of this Monte Carlo simulation study and future empirical investigation possibilities are both discussed.     

一类Pythagoras问题的推广

设x,y,z是正整数.若x2+y2=z2,则称(x,y,z)是一组Pythagoras数.本文运用初等方法证明了:(1)恰有12组Pythagoras数(x,y,z)满足2p(x,y,z)=xy,其中p为奇素数;(2)恰有36组Pythagoras数(x,y,z)满足2pq(x+y+z)=xy,其中p,q均为奇素数,且p相似文献   

1×4格牌覆盖棋盘的计数

设 f(m,n)为 1× 4格牌覆盖 m× n棋盘的方法数 ,用递推的方法给出 f(m,n)(m=4,5,6,7)的递推式及生成函数     

基于多用户OFDM和分布式天线的认知无线电中最优子载波分配方案

分别在平坦衰落和频率选择性衰落的无线信道模型中建立了基于多用户正交频分复用技术（OFDM）和分布式天线的认知无线电系统中子载波分配模型.该模型不再用＂干扰温度＂限制认知用户来保护主用户,而是规定主用户在其所有子载波上的吞吐量之和需要高于一定的门限.然后,根据不同信道模型的特点提出了最优子载波分配方案,该方案利用分支定界法和隐枚举法最大化系统的吞吐量.最后,利用Pegging算法提出了效率与公平折中的子载波分配方案.仿真证明,在不同场景中所提出的子载波分配方案与现有方案相比在吞吐量和公平性方面均具有较大的优势.     

聚甲醛链构象熵的研究

把聚甲醛（ＰＯＭ）链的主链分成Ａ、Ｂ两类,Ａ类以碳原子作为起始原子,Ｂ类以氧原子作为超始原子。用完全计算法计算了考虑排斥体积的Ａ、Ｂ两类甲醛链的构象熵ＳＡ和Ｓａ链长为奇数时,ＳＡ＝Ｓａ链长为偶数时,ＳＡ〉Ｓａ,两者之间的差别很小,而且随链长的增长而减小。因此,对于ＰＯＭ长链,可以不考虑Ａ、Ｂ之间的差别,认为ＳＡ＝Ｓａ。结果表明,聚甲醛边的构象熵跟链长成正比,随温度的升高而增大,在约２５Ｋ时等于０。