Quality measures for soil surveys by lognormal kriging

If we know the variogram of a random variable then we can compute the prediction error variances (kriging variances) for kriged estimates of the variable at unsampled sites from sampling grids of different design and density. In this way the kriging variance is a useful pre-survey measure of the quality of statistical predictions, which can be used to design sampling schemes to achieve target quality requirements at minimal cost. However, many soil properties are lognormally distributed, and must be transformed to logarithms before geostatistical analysis. The predicted values on the log scale are then back-transformed. It is possible to compute the prediction error variance for a prediction by this lognormal kriging procedure. However, it does not depend only on the variogram of the variable and the sampling configuration, but also on the conditional mean of the prediction. We therefore cannot use the kriging variance directly as a pre-survey measure of quality for geostatistical surveys of lognormal variables. In this paper we present an alternative. First we show how the limits of a prediction interval for a variable predicted by lognormal kriging can be expressed as dimensionless quantities, proportions of the unknown median of the conditional distribution. This scaled prediction interval can be used as a presurvey quality measure since it depends only on the sampling configuration and the variogram of the log-transformed variable. Second, we show how a similar scaled prediction interval can be computed for the median value of a lognormal variable across a block, in the case of block kriging. This approach is then illustrated using variograms of lognormally distributed data on concentration of elements in the soils of a part of eastern England

Recent advances in lightweight, filament-wound composite pressure vessel technology

A review of recent advances is presented for lightweight, high performance composite pressure vessel technology that covers the areas of design concepts, fabrication procedures, applications, and performance of vessels subjected to single cycle burst and cyclic fatigue loading. Filament wound fiber/epoxy composite vessels were made from S glass, graphite, and Kevlar 49 fibers and were equipped with both structural and nonstructural liners. Pressure vessels structural efficiencies were attained which represented weight savings, using different liners, of 40 to 60 percent over all titanium pressure vessels. Significant findings in each area are summarized

Hybrid composite laminate structures

An invention which relates to laminate structures and specifically to essentially anisotropic fiber composite laminates is described. Metal foils are selectively disposed within the laminate to produce increased resistance to high velocity impact, fracture, surface erosion, and other stresses within the laminate

New cubic self-dual codes of length 54, 60 and 66

We study the construction of quasi-cyclic self-dual codes, especially of binary cubic ones. We consider the binary quasi-cyclic codes of length 3\ell with the algebraic approach of [9]. In particular, we improve the previous results by constructing 1 new binary [54, 27, 10], 6 new [60, 30, 12] and 50 new [66, 33, 12] cubic self-dual codes. We conjecture that there exist no more binary cubic self-dual codes with length 54, 60 and 66.Comment: 8 page

Policy Framework for Outreach, Enrollment, Retention and Utilization for Health Care Coverage in California

Defines a framework that counties in California can use to structure outreach, enrollment, retention, and utilization systems and strategies. Provides specific recommendations, based on local successes, for improving access to health care by children

Differences in Mental Health and Ethnic-Racial Identity between White Gender Variant Students and Gender Variant Students of Color

Differences in Mental Health and Ethnic-Racial Identity between White Gender Variant Students and Gender Variant Students of Color Xuxa Sky Lark, Depts. of International Social Justice and French, Arlenis Santana, Dept. of Psychology Graduate Student, & Chloe Walker, Dept. of Psychology Graduate Student, with Dr. Diamond Y. Bravo, Dept. of Psychology, University of California, Riverside, and Dr. Chelsea Derlan Williams, Dr. Amy Adkins, and Dr. Danielle M. Dick, Dept. of Psychology Gender variant college students (i.e., transgender, genderqueer, and questioning) experience increased risk for mental health disparities, discrimination, bullying, family disownment, homelessness, and hate crimes, to name a few (Eisenberg, 2017). Further disparities arise when the intersections of gender and race are both considered; however, few studies have tested ethnic-racial identity (ERI) development among gender variant individuals (Kattari, 2016), which is predominantly tested in cisgender populations (e.g., Aoyagi et al, 2017; Umaña-Taylor et al., 2014). This is a notable gap given that ERI is a normative aspect of adolescence and emerging adulthood that is associated with positive development (Umaña-Taylor et al., 2014). Understanding ERI and mental health among diverse gender variant individuals is important to be able to create effective interventions and resources across ethnic-racial backgrounds that considers individuals’ unique lived experiences (Mossakowski, 2003). To address these gaps, the current study, grounded in the minority stress framework (Meyer, 2003) and ERI frameworks (Umaña-Taylor et al., 2014), tested differences in mental health (i.e., anxiety and depression) and ERI (i.e., exploration, resolution, and affirmation) between White gender variant students and gender variant students of color. The sample in the current study was from a larger university-wide study (i.e., Spit for Science; Dick et al., 2014), and consisted of 112 ethnically diverse gender variant students who identified as a White student (n = 72) or identified as a student of color (n = 40) in college. Students ranged in age from 18-24 years old (M = 20.15, SD = 1.61), and were 4.6% transgender women, 11.11% transgender men, 30.16% questioning, and 53.97% genderqueer. The Symptom Checklist 90-R (SCL-90-R; Derogatis & Cleary, 1977) was used to measure levels of depression and anxiety, and the Ethnic Identity Scale-Brief (EIS-B; Douglass & Umaña-Taylor, 2015) was used to assess ERI exploration, resolution, and affirmation. First, descriptive statistics were conducted to examine correlations among variables (Table 1). Next, hypotheses were tested with five t-tests that tested mean differences in mental health and ERI between gender variant White students and students of color. Findings indicated gender variant students of color (compared to White gender variant students) had significantly higher ERI exploration (t (107) = -6.49, p = .00), ERI affirmation (t (106) = -2.23, p = .03), and ERI resolution (t (106) = -5.61, p = .00). Although gender variant students of color had higher mean levels of anxiety and depression than White gender variant students, this difference was not significant (p \u3e .05). Discussion will center on how ERI may be a protective factor for gender identity-based risk factors among gender variant students of color, which will be a fruitful area for continued investigation and intervention efforts.https://scholarscompass.vcu.edu/uresposters/1318/thumbnail.jp

Hygrothermomechanical evaluation of transverse filament tape epoxy/polyester fiberglass composites

The static and cyclic load behavior of transverse filament tape (TFT) fiberglass/epoxy and TFY fiberglass/polyester composites, intended for use in the design of low-cost wind turbine blades, are presented. The data behavior is also evaluated with respect to predicted properties based on an integrated hygrothermomechanical response theory. Experimental TFT composite data were developed by the testing of laminates made by using composite layups typical of those used for the fabrication of TFT fiberglass wind turbine blades. Static properties include tension, compression, and interlaminar shear strengths at ambient conditions and at high humidity/elevated temperature conditions after a 500 hour exposure. Cyclic fatigue data were obtained using similar environmental conditions and a range of cyclic stresses. The environmental (temperature and moisture) and cyclic load effects on composite strength degradation are subsequently compared with the predictions obtained by using the composite life/durability theory. The results obtained show that the predicted hygrothermomechanical environmental effects on TFT composites are in good agreement with measured data for various properties including fatigue at different cyclic stresses

Acoustic emission testing of composite vessels under sustained loading

Acoustic emissions (AE) generated from Kevlar 49/epoxy composite pressure vessels subjected to sustained load-to-failure tests were studied. Data from two different transducer locations on the vessels were compared. It was found that AE from vessel wall-mounted transducers showed a wide variance from those for identical vessels subjected to the same pressure loading. Emissions from boss-mounted transducers did, however, yield values that were relatively consistent. It appears that the signals from the boss-mounted transducers represent an integrated average of the emissions generated by fibers fracturing during the vessel tests. The AE from boss-mounted transducers were also independent of time for vessel failure. This suggests that a similar number of fiber fractures must occur prior to initiation of vessel failure. These studies indicate a potential for developing an AE test procedure for predicting the residual service life or integrity of composite vessels