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

Application of a novel method for soil aggregate stability measurement by laser granulometry with sonication

Aggregate stability is an important physical indicator of soil quality, and so methods are required to measure it rapidly and cost-effectively so that sufficient data can be collected to detect change with adequate statistical power. The standard methods to measure water-stable aggregates (WSA) in soil involve sieving, but these have limitations that could be overcome if the aggregates were measured with a laser granulometer (LG) instrument. We present a novel method in which a LG is used to make two measurements of the continuous size distribution (<2000 µm) of a sample of aggregates. The first measurement is made on the WSA after these have been added to circulating water (initial air-dried aggregate size range 1000–2000 µm). The second measurement is made on the disaggregated material (DM) after the circulating aggregates have been disrupted with ultrasound (sonication). We then compute the difference between the mean weight diameters (MWD) of these two size distributions; we refer to this value as the disaggregation reduction (DR; µm). Soils with more stable aggregates, which are resistant to both slaking and mechanical breakdown by the hydrodynamic forces during circulation, have larger values of DR. We applied this method to six and ten sub-samples, respectively, of soil aggregates (each ca. 0.3 g) from bulk soil material from two contrasting soil types from England, both under conventional tillage (CT). The mean DR values were, respectively, 178 and 30 µm, with coefficients of variation of 12.1 and 19% suggesting the DR value is reproducible for the small mass of soil used. We attribute the larger DR values to the greater abundance of micaceous clay minerals in one of the soils. The DR values computed for each Blackwater Drain (BD) sample after removal of organic matter (with hydrogen peroxide) were comparable to those subject to sonication suggesting that most of the aggregate structure is removed by sonication. We used aggregates (1000–2000 µm) from soil samples collected at 30 locations under CT (median soil organic carbon (SOC) = 1.4%) across two types of parent material in the Blackwater drain sub-catchments of the Wensum catchment (Norfolk, UK). These soils had no coarse WSA, so we rescaled the size distributions to estimate DR for particle diameters <500 µm. Dithionite-extractable iron concentration, plus a minor contribution from parent material class, accounted for 64% of the variation in rescaled DR highlighting the importance of crystalline iron oxyhydroxides for aggregate stability in this region where long-term arable production has reduced top-soil SOC concentrations. We discuss how this technique could be developed to monitor aggregate stability as a soil physical indicator

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

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

Titanium/beryllium laminates: Fabrication, mechanical properties, and potential aerospace applications

The investigation indicated that structural laminates can be made which have: a modulus of elasticity comparable to steel, fracture strength of comparable to the yield strength of titanium, density comparable to aluminum, impact resistance comparable to titanium, and little or no notch sensitivity. These laminates can have stiffness and weight advantages over other materials including advanced fiber composites, in some aerospace applications where buckling resistance, vibration frequencies, and weight considerations control the design

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

The Decision Value Computations in the vmPFC and Striatum Use a Relative Value Code That is Guided by Visual Attention

There is a growing consensus in behavioral neuroscience that the brain makes simple choices by first assigning a value to the options under consideration and then comparing them. Two important open questions are whether the brain encodes absolute or relative value signals, and what role attention might play in these computations.Weinvestigated these questions using a human fMRI experiment with a binary choice task in which the fixations to both stimuli were exogenously manipulated to control for the role of visual attention in the valuation computation. We found that the ventromedial prefrontal cortex and the ventral striatum encoded fixation-dependent relative value signals: activity in these areas correlated with the difference in value between the attended and the unattended items. These attention-modulated relative value signals might serve as the input of a comparator system that is used to make a choice

A new class of codes for Boolean masking of cryptographic computations

We introduce a new class of rate one-half binary codes: {\bf complementary information set codes.} A binary linear code of length $2n$ and dimension $n$ is called a complementary information set code (CIS code for short) if it has two disjoint information sets. This class of codes contains self-dual codes as a subclass. It is connected to graph correlation immune Boolean functions of use in the security of hardware implementations of cryptographic primitives. Such codes permit to improve the cost of masking cryptographic algorithms against side channel attacks. In this paper we investigate this new class of codes: we give optimal or best known CIS codes of length $<132.$ We derive general constructions based on cyclic codes and on double circulant codes. We derive a Varshamov-Gilbert bound for long CIS codes, and show that they can all be classified in small lengths $\le 12$ by the building up construction. Some nonlinear permutations are constructed by using $\Z_4$-codes, based on the notion of dual distance of an unrestricted code.Comment: 19 pages. IEEE Trans. on Information Theory, to appea

Advanced fiber-composite hybrids--A new structural material

Introduction of metal foil as part of matrix and fiber composite, or ""sandwich'', improves strength and stiffness for multidirectional loading, improves resistance to cyclic loading, and improves impact and erosion resistance of resultant fiber-composite hybrid structure

Controlling the marginal false discovery rate in inferences from a soil dataset with α -investment

Large datasets on soil provide a temptation to search for relations between variables and then to model and make inferences about them with statistical methods more properly used to test preplanned hypotheses on data from designed experiments or sample surveys. The control of family-wise error rate (FWER) is one way to improve the robustness of inferences from tests of multiple hypotheses. In its simplest form, hypothesis testing with FWER control lacks statistical power. The α-investment approach to controlling the marginal false discovery rate is one method proposed to improve statistical power. In this paper I outline the α-investment approach and then demonstrate it in the analysis of a dataset on the rate of CO2 emission from incubated intact cores of soil from a transect over Cretaceous rocks in eastern England. Hypotheses are advanced after considering the literature and examining relations among the available soil variables that might be proposed as explanatory factors for the variation of CO2 emissions. They are then tested in sequence with α-investment, such that the rejection of null hypotheses increases the power to reject later ones, while controlling the overall marginal false discovery rate at a specified value. This paper illustrates the use of α-investment to test a multiple set of hypotheses on a soil dataset; statistical power is improved by ordering the sequence of hypotheses on the basis of process knowledge. The approach could be useful in other areas of soil science where covariates must be selected for predictive statistical models, notably in the development of pedotransfer functions and in digital soil mapping. Highlights α-investment controls marginal false discovery rate in statistical inference. Hypotheses were advanced about soil factors that affect CO2 emission from soil. These hypotheses were tested in sequence with control of marginal false discovery rate. Soil properties, land use and parent material were significant predictors