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• The current study demonstrates how incubation periods can be used to evaluate children's personal (i.e., child-level) originality. • Study findings provide preliminary convergent validity evidence for an author-developed, "personal-originality" approach for scoring children's divergent thinking. • Children's original ideation in verbal divergent thinking tasks is supported by short (i.e., 2 min) incubation periods. Divergent thinking, which can be described as the ability to conceive of and express a variety of novel solutions to open-ended problems (Gibson et al., 2009), is one of the most commonly studied constructs related to creative thinking. There is considerable evidence that divergent thinking is predictive of later creative behavior and achievement. However, current methods depend heavily on social comparison as a means for operationalizing children's divergent thinking outcomes, which may diminish the ability to detect key indicators of creative potential, such as child-level originality. The current study introduces a child-level, "personal-originality" approach to scoring children's performance in common divergent thinking tasks. While originality is often assessed in terms of statistical rarity or subjective ratings, personal-originality scoring captures divergent thinking at the child level through the strategic use of incubation periods. That is, children demonstrate personal originality by producing new ideas after time away from the task. The current study explored the effects of a 2 min incubation period on 42 three- to six-year-olds' divergent thinking performance. Results indicate children do, indeed, produce original ideas after time off-task. Moreover, the personal-originality outcome measure introduced in the present study demonstrated strong evidence of convergent validity. [ABSTRACT FROM AUTHOR]

Abstract: High fidelity measurements of constituent particle or corrosion topography nucleated fatigue crack growth rates (da/dN) are established for 7075-T651 in humid air. Values of microstructure-scale da/dN are determined by microscopy of programmed load-induced crack surface markers, rather than surface-only measurements. Both pristine and corroded specimen da/dN from various applied stress levels are successfully correlated using continuum-elastic stress intensity (ΔK or ΔK and K max) or dislocation-based (Bilby–Cottrell–Swindon) crack tip opening displacement (cyclic ϕ and ϕ max), with the former accounting for the gradient of elastic stress concentration due to the initiating feature. Values of da/dN vary by an order of magnitude at each fixed driving force due to microstructural influences that result in a locally irregular crack front. Grain-scale models using stress intensity closure or slip-based crystal plasticity do not capture experimental da/dN variability. Due to an inadequate mechanistic basis, mechanics-inspired models of da/dN do not predict multiple growth regimes that are typical of environment enhanced cracking. An elastic ΔK-based description of long crack da/dN data for a given alloy-environment can be transformed to a continuum elastic–plastic ϕ c basis to provide a mean crack growth rate description. Coupling mean rates with a statistical description of microstructure sensitive variability, and dislocation or crystal plasticity-finite element modeling of component ϕ c for non-continuum cracking, will enhance prognosis in the MSC regime. [Copyright &y& Elsevier]

Abstract: This study investigates the relationship between surface street traffic volume and single-family house prices in a relatively small city in the US. Hedonic price models are estimated using data from 9670 transactions that occurred between January 1998 and March 2011. It is discovered that parcels fronting or adjacent to a high-traffic street sell, on average, at an 8.1% discount compared to similar parcels that are not so situated. Restricting the analysis to parcels on or adjacent to a high-traffic street, house price and traffic volume are found to be negatively related; a doubling of volume from any particular traffic count, ceteris paribus, reduces selling price by an average of 2.1%. [Copyright &y& Elsevier]

Abstract: The effect of stress ratio on the statistical aspects of small fatigue crack growth behavior was studied in a duplex microstructure of Ti–6Al–2Sn–4Zr–6Mo (Ti-6-2-4-6) at 260°C with particular emphasis on incorporating small-crack data into probabilistic life prediction and the influence of stress ratio on probabilistic lifetime limits. A Focused Ion Beam (FIB) was used to machine micro-notches in test specimens, which served as crack-initiation sites and enabled the acquisition of multiple small-crack growth data sets from single experiment. Stress ratios of −0.5, 0.05, and 0.5 were employed, and small-crack growth was monitored by the acetate replication method. Qualitatively, change in the stress ratio produced almost negligible influence on the small-crack growth behavior when plotted as crack growth rate (da/dN) vs. applied stress intensity factor range (ΔK). A probabilistic method was employed to represent the variability in the small-crack growth behavior and the statistical differences with respect to stress ratio where a method of optimization of the small-crack growth model parameters, based on a minimization of the error between the predicted and the measured crack length vs. cycles (a vs. N) data, was used. In spite of qualitative similarity, differences in the statistical parameters of small-crack growth as a function of stress ratio were found to be significant in life prediction. The methods for representation and probabilistic treatment of small-crack data were also shown to be important factors in incorporation of the small-crack regime in probabilistic life prediction. [Copyright &y& Elsevier]

Fatigue crack-initiation sites in Ti–6Al–2Sn–4Zr–6Mo (Ti–6–2–4–6), an α + β titanium alloy used in turbine engine applications, were characterized with emphasis on distinguishing the microstructural neighborhoods and mechanisms that produce the life-limiting failures vs. those that promote the mean-lifetime behavior. The characterization methods included quantitative tilt fractography, focused ion beam milling across crack-initiation facets, and electron backscattered diffraction analysis. The motivation for discerning between the life-limiting and the mean-dominating crack-initiation microstructural neighborhoods stemmed from the previously developed understanding that the mean and the life-limiting behaviors respond differently to stress level (and many other variables), leading to an increasing separation between the two subpopulations as the stress level is decreased, thereby increasing the variability in lifetime. The different rates of response of the two behaviors was found to arise because the life-limiting mechanism was dominated by the crack-growth lifetime, with microstructural-scale crack-initiation occurring within the first few fatigue cycles, whereas the mean behavior was increasingly dominated by the crack-initiation lifetime as the stress level was decreased. Representative specimens for 2-D characterization of crack-initiation neighborhoods were selected from life-limiting and mean-dominating populations generated by fatigue tests on a duplex α + β phase microstructure of Ti–6–2–4–6 under a narrow range of applied stress amplitudes. A compilation of data on the crack-initiation facet and the neighborhood of the faceted grain from multiple specimens pointed to at least four categories of critical microstructural configurations, each representing a set of necessary (but perhaps not sufficient) conditions for crack-initiation in this alloy. Based on this characterization, a hypothesis for the life-limiting fatigue behavior is presented. The hypothesis invokes the concept of hierarchy of fatigue deformation heterogeneities, which is suggested to develop within the first few fatigue cycles. The deformation heterogeneity is suggested to be linked to the underlying randomness and hierarchy in the microstructural arrangements. This hypothesis appears to explain the occurrence of crack-growth-lifetime-dominated, life-limiting failures in the regime of high-cycle fatigue, as shown in this study, and suggests a probability of occurrence of such failures even in the very-high-cycle fatigue regime, although with diminishing probability as the stress level is decreased. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fatigue life data were analyzed for bimodal (FCG or initiation-dominated) behavior. [•] Short life populations were observed preferentially under more aggressive conditions. [•] Short lives were consistent with FCP lives, supported by micro-notched tests. [•] Relative sampling of two mechanisms affected accuracy of uni-modal predictions. [•] Crack growth-dominated lives were most readily assessed via electropolished samples. [Copyright &y& Elsevier]

Shot-peen residual stress relaxation due to thermal exposure and fatigue loading was characterized in Ti–6Al–2Sn–4Zr–6Mo. Approximately 80% of the residual stresses were retained at 399°C up to 100h. Under fatigue loading close to yield stress, retention of residual stresses was approximately 85%, 70% and 50% at 260, 316 and 399°C, respectively. Crack growth calculations demonstrate 1.5–5× benefit in life, even for partial credit for shot-peen residual stresses. [Copyright &y& Elsevier]