Fracture Mechanics of Two Dimensional Noncircular Flaws

The growth of two dimensional noncircular flaws was studied by three independent methods: transfer function analysis, equivalent area approximation, and direct fracture mechanics calculation. All three methods yield results varying within a few percent of one another for the simpler elliptical and rectangular geometries. Results of transfer function and equivalent area methods agree also within a few percent of each other for the more irregularly shaped flaws. The importance of these studies to NDE predictive technology is discussed

Morphological variation of the foraminifer Ammonia beccarii (Linné) from the Atlantic coast of the United States

24 p., 4 fig.http://paleo.ku.edu/contributions.htm

Impact of particle shape on electron transport and lifetime in zinc oxide nanorod-based dye-sensitized solar cells

Owing to its high electron mobility, zinc oxide represents a promising alternative to titanium dioxide as the working electrode material in dye-sensitized solar cells (DSCs). When zinc oxide is grown into 1-D nanowire arrays and incorporated into the working electrode of DSCs, enhanced electron dynamics and even a decoupling of electron transport (τd) and electron lifetime (τn) have been observed. In this work, DSCs with working electrodes composed of solution-grown, unarrayed ZnO nanorods are investigated. In order to determine whether such devices give rise to similar decoupling, intensity modulated photocurrent and photovoltage spectroscopies are used to measure τd and τn, while varying the illumination intensity. In addition, ZnO nanorod-based DSCs are compared with ZnO nanoparticle-based DSCs and nanomaterial shape is shown to affect electron dynamics. Nanorod-based DSCs exhibit shorter electron transport times, longer electron lifetimes, and a higher τn/τd ratio than nanoparticle-based DSCs

Ground Motion Amplification from Vertical Propagation of Earthquake Waves

The paper is directed to follow a procedure where seismic responses are identified and recommendations to proceed with their applications are made quickly and economically, before engaging in a complex analysis. It is not intended for selecting design soil parameters or earthquake parameters for the final design of any specific dam. A selected earthquake accelerogram will produce response accelerations and strains that will cover a significant variety of accelerograms in terms of severity of earthquake damage to an earth dam. Scaling-up and scaling-down the selected outcrop motion broadens the spectrum of seismic response analyses using simple and effective SHAKE program for making decision on the need for further more sophisticated analyses, particularly when the 1-D response analysis shows potential problems. It is inappropriate to base the judgment of final seismic response of dam on 1-D analysis,. The traditional dynamic modulus reduction curves have been shown to be appropriate up to one percent strain. The analysis performed in this paper shows the maximum strain to be smaller than 0.5%. The Mexico City (MC) clay is used to demonstrate different soil types do exist in nature and, in some situation, can show quite different responses in different intensity seismic events. First, hypothetical soil deposits are used in evaluating factors affecting PHA variation in a soil deposit, and then, the findings are referenced in the seismic response of an embankment dam in the west coast of the United States. The shear wave velocities of this embankment dam were carefully selected, using educated judgment, to represent a compacted embankment

Analysis of mixed elliptic and parabolic boundary layers with corners

We study the asymptotic behavior at small diffusivity of the solutions, u??, to a convection-diffusion equation in a rectangular domain. The diffusive equation is supplemented with a Dirichlet boundary condition, which is smooth along the edges and continuous at the corners. To resolve the discrepancy, on ???, between u?? and the corresponding limit solution, u0, we propose asymptotic expansions of u?? at any arbitrary, but fixed, order. In order to manage some singular effects near the four corners of , the so-called elliptic and ordinary corner correctors are added in the asymptotic expansions as well as the parabolic and classical boundary layer functions. Then, performing the energy estimates on the difference of u?? and the proposed expansions, the validity of our asymptotic expansions is established in suitable Sobolev spaces.open

Bayesian Model Averaging for Clustered Data: Imputing Missing Daily Air Pollution Concentration

The presence of missing observations is a challenge in statistical analysis especially when data are clustered. In this paper, we develop a Bayesian model averaging (BMA) approach for imputing missing observations in clustered data. Our approach extends BMA by allowing the weights of competing regression models for missing data imputation to vary between clusters while borrowing information across clusters in estimating model parameters. Through simulation and cross-validation studies, we demonstrate that our approach outperforms the standard BMA imputation approach where model weights are assumed to be the same for all clusters. We then apply our proposed method to a national dataset of daily ambient coarse particulate matter (PM10-2.5) concentration between 2003 and 2005. We impute missing daily monitor-level PM10-2.5 measurements and estimate the posterior probability of PM10-2.5 nonattainment status for 95 US counties based on the Environmental Protection Agency\u27s proposed 24-hour standard

Traffic-related air pollution and obesity formation in children: a longitudinal, multilevel analysis.

BackgroundBiologically plausible mechanisms link traffic-related air pollution to metabolic disorders and potentially to obesity. Here we sought to determine whether traffic density and traffic-related air pollution were positively associated with growth in body mass index (BMI = kg/m2) in children aged 5-11 years.MethodsParticipants were drawn from a prospective cohort of children who lived in 13 communities across Southern California (N = 4550). Children were enrolled while attending kindergarten and first grade and followed for 4 years, with height and weight measured annually. Dispersion models were used to estimate exposure to traffic-related air pollution. Multilevel models were used to estimate and test traffic density and traffic pollution related to BMI growth. Data were collected between 2002-2010 and analyzed in 2011-12.ResultsTraffic pollution was positively associated with growth in BMI and was robust to adjustment for many confounders. The effect size in the adjusted model indicated about a 13.6% increase in annual BMI growth when comparing the lowest to the highest tenth percentile of air pollution exposure, which resulted in an increase of nearly 0.4 BMI units on attained BMI at age 10. Traffic density also had a positive association with BMI growth, but this effect was less robust in multivariate models.ConclusionsTraffic pollution was positively associated with growth in BMI in children aged 5-11 years. Traffic pollution may be controlled via emission restrictions; changes in land use that promote jobs-housing balance and use of public transit and hence reduce vehicle miles traveled; promotion of zero emissions vehicles; transit and car-sharing programs; or by limiting high pollution traffic, such as diesel trucks, from residential areas or places where children play outdoors, such as schools and parks. These measures may have beneficial effects in terms of reduced obesity formation in children