Thermal expansion of graphite-epoxy between 116 K and 366 K

A Priest laser interferometer was developed to measure the thermal strain of composite laminates. The salient features of this interferometer are that: (1) it operates between 116 K and 366 K; (2) it is easy to operate; (3) minimum specimen preparation is required; (4) coefficients of thermal expansion in the range of 0-5 micro epsilon/K can be measured; and (5) the resolution of thermal strain is on the order of micro epsilon. The thermal response of quasi-isotropic, T300/5208, grahite-epoxy composite material was studied with this interferometer. The study showed that: (1) for the material tested, thermal cycling effects are negligible; (2) variability of thermal response from specimen to specimen may become significant at cryogenic temperatures; and (3) the thermal response of 0.6 cm and 2.5 cm wide specimens are the same above room temperature

Development of a Priest interferometer for measurement of the thermal expansion of a graphite epoxy in the temperature range 116-366 K

The thermal expansion behavior of graphite epoxy laminates between 116 and 366 degrees Kelvin was investigated using as implementation of the Priest interferometer concept. The design, construction and use of the interferometer along with the experimental results it was used to generate are described. The experimental program consisted of 25 tests on 25.4 mm and 6.35 mm wide, 8 ply pi/4 quasi-isotropic T300-5208 graphite/epoxy specimens and 3 tests on a 25.4 mm wide unidirectional specimen. Experimental results are presented for all tests along with a discussion of the interferometer's limitations and some possible improvements in its design

Development and Preliminary Application of Mathematical Models to the Weber Basin

The adoption of stream standards, whether for direct application or for the establishment of realistic effluent standards, creates a need to predict the impact of pollution loads on river water quality during critical flow periods or as the result of future user demands. Because of the complexity of aquatic systems, mathematical models are an excellent medium for bringing together the state-of-the-art knowledge from a variety of disciplines into a form which can be readily applied to practical problems. Applying a mathematical model to a river system has the added advantage of providing a structure for the systematic consideration of the many diverse aspects of water quality phenomena. This report describes the development of a river simulation model (QUAL-U) for predicting water quality and its preliminary application to the Weber River drainage basin in northeastern Utah. The model involves the numerical solution of a set of differential equations representing the aquatic system under steady state conditions. The development and use of a second model which provides the flow boundary conditions for the first model is also described. This model is a simple interactive procedure for obtaining flows at specified locations on the river system given the measured flows at other locations and typical flow ranges of headwater, diversions, surface and subsurface lateral inflows, and point loads. Previous river water quality models are reviewed and the structure of QUAL-U is presented. The economic and physical characteristics of the study area are described and the Weber River system is represented by subbasins, reaches, and computational units. Model calibration was based on water quality data collected at over eighty sampling locations in the study area during a four day period in September, 1973. Each of the sampling points was subsequently surveyed to obtain representative hydraulic characteristics for each reach of the river system. Coefficients for the mathematical equations representing hydraulic characteristics and chemical and biological reactions were estimated and adjusted during the model calibration procedure until model responses satisfactorily resembled the observed data. Results for the calibration period and also for studies involving critical low flow conditions are described and model limitations are considered. The work on which this report is based was performed for the State of Utah, Department of Social Services, Division of Health as part of a Waste Load Allocation Study on the Weber River. The scope of this project provided only for supplying the calibrated model to the client and does not include predictive runs or interpretation of management alternatives

Designing for time-dependent material response in spacecraft structures

To study the influence on overall deformations of the time-dependent constitutive properties of fiber-reinforced polymeric matrix composite materials being considered for use in orbiting precision segmented reflectors, simple sandwich beam models are developed. The beam models include layers representing the face sheets, the core, and the adhesive bonding of the face sheets to the core. A three-layer model lumps the adhesive layers with the face sheets or core, while a five-layer model considers the adhesive layers explicitly. The deformation response of the three-layer and five-layer sandwich beam models to a midspan point load is studied. This elementary loading leads to a simple analysis, and it is easy to create this loading in the laboratory. Using the correspondence principle of viscoelasticity, the models representing the elastic behavior of the two beams are transformed into time-dependent models. Representative cases of time-dependent material behavior for the facesheet material, the core material, and the adhesive are used to evaluate the influence of these constituents being time-dependent on the deformations of the beam. As an example of the results presented, if it assumed that, as a worst case, the polymer-dominated shear properties of the core behave as a Maxwell fluid such that under constant shear stress the shear strain increases by a factor of 10 in 20 years, then it is shown that the beam deflection increases by a factor of 1.4 during that time. In addition to quantitative conclusions, several assumptions are discussed which simplify the analyses for use with more complicated material models. Finally, it is shown that the simpler three-layer model suffices in many situations

The BetaCage, an ultra-sensitive screener for surface contamination

Material screening for identifying low-energy electron emitters and alpha-decaying isotopes is now a prerequisite for rare-event searches (e.g., dark-matter direct detection and neutrinoless double-beta decay) for which surface radiocontamination has become an increasingly important background. The BetaCage, a gaseous neon time-projection chamber, is a proposed ultra-sensitive (and nondestructive) screener for alpha- and beta-emitting surface contaminants to which existing screening facilities are insufficiently sensitive. Sensitivity goals are 0.1 betas per keV-m$^2$-day and 0.1 alphas per m$^2$-day, with the former limited by Compton scattering of photons in the screening samples and (thanks to tracking) the latter expected to be signal-limited; radioassays and simulations indicate backgrounds from detector materials and radon daughters should be subdominant. We report on details of the background simulations and detector design that provide the discrimination, shielding, and radiopurity necessary to reach our sensitivity goals for a chamber with a 95$\times$95 cm$^2$ sample area positioned below a 40 cm drift region and monitored by crisscrossed anode and cathode planes consisting of 151 wires each.Comment: 5 pages, 3 figures, Proceedings of Low Radioactivity Techniques (LRT) 2013, Gran Sasso, Italy, April 10-12, 201

Long-term Aquatic Invertebrate Monitoring at Buffalo National River, Arkansas

Aquatic invertebrate community structure was used to assess long-term water quality integrity in the mainstem of the Buffalo National River, Arkansas from 2005 to 2013. Nine benthic invertebrate samples were collected from each of six sampling sites using a Slack-Surber sampler. The Stream Condition Index (SCI) developed for Ozark streams was used to assess integrity of the invertebrate communities. This index is calculated using taxa richness, EPT (Ephemeroptera, Plecoptera, Trichoptera) Richness, Shannon’s Diversity Index, and Hilsenhoff Biotic Index (HBI). Sørensen’s similarity index was used to assess community similarity among sites, and scores were then analyzed using ascendant hierarchical cluster analysis. The benthic invertebrate fauna was diverse with 167 distinct taxa identified from all sites, with similarities ranging from 70% to 83%. Cluster analysis showed that sites were clustered in a longitudinal progression, with those sites closest to one another in linear distance generally being the most closely related. Overall, the invertebrate taxa of the Buffalo River are largely intolerant (mean tolerance value= 4.38). Taxa richness was typically greater than 20 among samples, and EPT richness values consistently were greater than 12 for all sites in most years. Shannon’s diversity index values generally ranged from 2.0 to 2.5 among sites and years. Metric values tended to decrease in a downstream direction to Site 4, and then increase to levels observed upstream. The exception was for HBI, which did not show this response and values for this metric generally were below 5. SCI scores among sampling sites were variable but not generally impaired and were fully biologically-supporting. Water quality (temperature, dissolved oxygen, specific conductance, pH, turbidity) met state standards in all instances. Habitat data were summarized, but found to be poorly correlated with invertebrate metrics (\u3c30% significant). Although the condition of invertebrate communities and water quality in the Buffalo River are largely sound and have high integrity, numerous ongoing and projected threats to these resources remain, and those threats largely originate outside of the park’s jurisdictional boundaries. Inherent variability of invertebrate community diversity and density across sites and years highlights the importance of using multi-metric assessment and multiyear monitoring to support management decisions

A New Solid Deuterium Source of Ultra-Cold Neutrons

In polarized neutron decay, the angular correlation between the neutron spin and the direction of emission of the electron is characterized by the coefficient A. Measuring A involves determining the forward-backward asymmetry of the decay beta with respect to the direction of the neutron polarization. The value of A, when combined with measurements of the neutron lifetime, determines the values of the vector and axial vector weak coupling constants, Gv and GA. The value of Gv can also be determined by measurements of superallowed nuclear beta decay and by requiring that the Cabibo-Kobayashi-Maskawi (CKM) mixing matrix be unitary along with the measured value of other elements of the CKM matrix

Stochastic Interpolation of Precipitation Data From Multiple Sensors

Introduction: This report summarizes the work conducted under Grant No. ECE-8419189, Stochastic Interpolation of Precipitation Data from Multiple Sensors, which was awarded to Utah State University in September, 1985, and completed February 29, 1988. it also covers work under a supplemental award made in February, 1986. The final report is organized into four sections. The following section presents the objective of the research and a brief problem statment. Section 3 contains a summary of second-year work including the project team, work plan, work completed, and publications. In Section4, project conclusions are summarized. A summary of on-going future work is given in Section 5, together with our plans for publication of research results from this project. Copies of preliminary draft manuscripts and completed technical reports which have been prepared as a result of second-year activities are contained in the Appendices. A cummulative summary of project publications is presented in Appendix A

Public health job advertisements in Australia and New Zealand: a changing landscape

Objective: To describe available public health jobs in Australia and New Zealand by comparing recent job advertisements. Methods: We screened vacancies from 14 online job boards for public health jobs in late 2018. Data collected included information on job titles, sector, contract tenure, location and salary. We compared our findings with those of a job advertisements study from 2005. Results: We found 333 public health job advertisements in Australia and New Zealand. Common roles included project officers, researchers and managers. Nearly 40% of jobs asked for a ‘tertiary’ degree, with an additional 20% requiring a PhD degree. A qualification in public health was considered essential in 13% of job advertisements. Median annual salary range was $95,000–$111,365. Conclusions: There is not one specific public health job. Instead, such jobs are diverse in role, sector, qualification level required and the salary they confer. Implications for public health: There is a demand for skilled workers to perform increasingly complex public health functions, but this may eventually be outpaced by graduate supply. Furthermore, while salaries are considerable, long-term positions are not, and this has implications for the sustainability of the public health workforce