An algorithm for unsteady flows with strong convection

An implicit ADI numerical method for the calculation of 2-D unsteady flows with strong convection effects is described. The method is based on the conventional Crank-Nicholson approach for parabolic equations but an upwind-downwind differencing is used for the first order spatial derivatives associated with convection. The differencing is carried out in the current and previous time plane in such a way that the algorithm is second order accurate in both space and time. The difference equations are factored into sequential operators, one in each independent spatial variable; the solution at each time step may then be computed as a sequence of tridiagonal matrix problems. The method may be used in a noniterative manner although iteration at each time step is recommended in situations where the effects of convection are strong

HRXRD study of the theoretical densities of novel reactive sintered boride candidate neutron shielding materials

Reactive Sintered Borides (RSBs) are novel borocarbide materials derived from FeCr-based cemented tungsten (FeCr-cWCs) show considerable promise as compact radiation armour for proposed spherical tokamak,[1],[2],[3],[4],[5]. Six candidate compositions (four RSBs, two cWCs) were evaluated by high-resolution X-ray diffraction (XRD), inductively coupled plasma (ICP), energy dispersive X-ray analysis (EDX) and scanning electron microscopy (SEM) to determine the atomic composition, phase presence, and theoretical density. RSB compositions were evaluated with initial boron contents equivalent to 25 at% 30 at%. All RSB compositions showed delamination and carbon enrichment in the bulk relative to the surface, consistent with non-optimal binder removal and insufficient sintering time. Phase abundance within RSBs derived from powder XRD was dominated by iron tungsten borides (FeWB/FeW2B2), tungsten borides (W2B5/WB) and iron borides. The most optimal RSB composition (B5T522W) with respect to physical properties and highest ρ/ρtheo had ρtheo = 12.59 ± 0.01 g cm-3 for ρ/ρtheo = 99.3% and had the weigh-in and post-sintered W : B : Fe abundance closest to 1 : 1 : 1. This work indicates that despite their novelty, RSB materials can be optimized and in principle be processed using existing cWC processing routes

JMASM9: Converting Kendall’s Tau For Correlational Or Meta-Analytic Analyses

Expanding on past research, this study provides researchers with a detailed table for use in meta-analytic applications when engaged in assorted examinations of various r-related statistics, such as Kendall’s tau (τ) and Cohen’s d, that estimate the magnitude of experimental or observational effect. A program to convert from the lesser-used tau coefficient to other effect size indices when conducting correlational or meta-analytic analyses is presented

JMASM19: A SPSS Matrix For Determining Effect Sizes From Three Categories: r And Functions Of r, Differences Between Proportions, And Standardized Differences Between Means

The program is intended to provide editors, manuscript reviewers, students, and researchers with an SPSS matrix to determine an array of effect sizes not reported or the correctness of those reported, such as rrelated indices, r-related squared indices, and measures of association, when the only data provided in the manuscript or article are the n, M, and SD (and sometimes proportions and t and F (1) values) for twogroup designs. This program can create an internal matrix table to assist researchers in determining the size of an effect for commonly utilized r-related, mean difference, and difference in proportions indices when engaging in correlational and/or meta-analytic analyses

A Comparison of Eight Shrinkage Formulas under Extreme Conditions

The performance of various shrinkage formulas for estimating the population squared multiple correlation coefficient (ρ2) were compared under extreme conditions often found in educational research with small sample sizes of 10, 15, 20, 25, 30 and regressor variates ranging from 2 to 4. A new formula for estimating ρ2, Adj R2 DW, was examined in terms of its performance under various conditions of N, p, ρ2, along with its bias properties and standard error estimates. The two shrinkage formulas that performed most consistently were the Claudy (Adj R2 C) and Walker (Adj R2 DW

A Comparison of the Spearman-Brown and Flanagan-Rulon Formulas for Split Half Reliability under Various Variance Parameter Conditions

Differences between the Spearman-Brown and Flanagan-Rulon formulas are examined when the variance parameters for two halves of a test had the following ratios: 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0 and also had a correlation between the two halves of a test at 1.00, .95, .90, .80, .70, .60, .50, .40, .30, .20, .10, .05. It was found that use of the Spearman-Brown formula to estimate the population ρ when the ratio between the standard deviations on two halves of a test is disparate, or beyond .9 to 1.1, was not warranted. Applied and theoretical examples are employed, as well as syntax for user application

Estimating How Many Observations are Needed to Obtain a Required Level of Reliability

This article provides a detailed table containing estimations of how many observations are needed to obtain an increased reliability coefficient for situations such as observational data collection in the classroom. A SPSS program is provided for users to analyze situations where an initial reliability value is obtained and the user wants to determine how many more observations are needed to reach a required level of reliability

Validation Studies: Matters Of Dimensionality, Accuracy, And Parsimony With Predictive Discriminant Analysis And Factor Analysis

Two studies were used as examples that examined issues of dimensionality, accuracy, and parsimony in educational research via the use of predictive discriminant analysis and factor analysis. Using a two-group problem, study 1 looked at how accurately group membership could be predicted from subjects’ test scores. Study 2 looked at the dimensionality structure of an instrument and if it developed constructs that would measure theorized domains

Bias Affiliated With Two Variants Of Cohen’s d When Determining U1 As A Measure Of The Percent Of Non-Overlap

Variants of Cohen’s d, in this instance dt and dadj, has the largest influence on U1 measures used with smaller sample sizes, specifically when n1 and n2 = 10. This study indicated that bias for variants of d, which influence U1 measures, tends to subside and become more manageable, in terms of precision of estimation, around 1% to 2% when n1 and n2 = 20. Thus, depending on the direction of the influence, both dt and dadj are likely to manage bias in the U1 measure quite well for smaller to moderate sample sizes

Prairie Republic: The Political Culture of Dakota Territory, 1879–1889

Review of: Prairie Republic: The Political Culture of Dakota Territory, 1879–1889, by Jon K. Lauck