旋流式气化炉冷态流场数值模拟研究

为探究一种新型旋流式气化炉冷态流场分布特性及内部结构对其流场的影响,应用计算流体力学( CFD)软件 FLUENT对该气化炉进行三维数值模拟分析。采用RNG K-8湍流模型,通过多点测压实验,对模拟结果进行验证,并且 采用不同的开孔率及旋流片角度组合分析气化炉内部结构对其流场的影响。结果表明：模拟和测压实验结果较为一致; 旋流式气化炉内气流主要做螺旋上升运动;栅板开孔率大小主要影响气化炉内压降、轴向速度以及湍流强度;而旋流片 角度则主要影响切向速度及湍流强度分布。新型旋流式气化炉内部栅板旋流片结构可增加气化反应速率及反应停留 时间,有助于气化反应的进行。     

Analysis of covariance in mixed models with unequal subclass numbers

Blue of estimable linear functions and exact tests of hypotheses concerning such functions usually do not exist in the covariance model with random factors having unknown variances. This is true even in the equal subclass numbers case. This paper suggests alternative methods for finding linear unbiased estimators and presents methods for computing sampling variances which are linear functions of the unknown parameter variances. Also, higher level covariates are defined and nonestimability problems resulting from association of such covariates with fixed factors are discussed.     

双层登普板结构采光屋面天幕系统施工技术

介绍双层登普板采光屋面天幕系统的结构、材料性能和施工技术．     

一类n阶迭代泛函微分方程解的存在唯一性

利用Banach不动点定理讨论一类带有初值条件的n阶迭代泛函微分方程解的存在性和唯一性.     

薄板屈曲后强度利用的探讨

不少国家已把薄板屈曲后强度可继续承受荷载列入钢结构设计规范.但我国<钢结构设计规范>(GBJ17-88)还没有这方面的条文规定.通过对薄板屈曲后强度的理论分析,得出了对工程设计有参考价值的结论.     

一类非单调二元算子新的不动点定理

利用锥理论和非对称迭代方法,讨论了不具有连续性和紧性条件的非单调二元算子方程解的存在唯一性,并给出了迭代序列收敛于解的误差估计,所得结果是某些已知结果的本质改进和推广.     

动词Быть的用法小结

在现代俄语中,动词是一个非常积极的词汇,而且其用法比较多,很难全面掌握。本文从该动词作独立动词、系词、助动词及一些固定搭配等几个方面对其用法进行了阐述。     

Modeling Repeatable Events Using Discrete‐Time Data: Predicting Marital Dissolution

I join two methodologies by illustrating the application of multilevel modeling principles to hazard‐rate models with an emphasis on procedures for discrete‐time data that contain repeatable events. I demonstrate this application using data taken from the 1995 National Survey of Family Growth (NSFG) to ascertain the relationship between multiple covariates and risk of subsequent marital dissolution. I consider both fixed‐ and random‐effects versions of the multilevel model, as well as a Generalized Estimating Equation alternative to estimating random effects. I compare results obtained from the various estimators, noting why differences occur, and recommend when to choose the various alternatives. I also provide a set of SAS and STATA programs that can be used to analyze the NSFG data.     

Computing factors for exact two-sided tolerance limits for a normal distribution

A self-contained FORTRAN subroutine is provided which computes factors for Wald-Wolfowitz type tolerance limits allowing arbitrary combinations of sample size n and degrees of freedom ν. The exact calculations from our program reveal inadequacies of two existing approximations, especially when ν ? n. Numerous applications where ν ≠ n ? 1 are cited; two of these are discussed and illustrated.