Electrical Control and Safety System for Solar Furnace

The Valparaiso University College of Engineering has recently received a donor gift and a federal earmark to design and manufacture a solar furnace facility. In the solar facility, a heliostat will reflect sunlight straight into the concentrator at every instant. However, due to manufacturing tolerances and inaccuracy in sun’s position model a sun sensor is added in the heliostat sun tracking system. The sun sensor fine adjusts the heliostat’s position so the reflected sunlight is normal to the concentrator. Our goal is to develop a sun sensor that provides an unbalanced output signal when the sensors receive an unbalanced light source. The plan is to implement the sun sensor on the quarter scale heliostat prototype in conjunction with a step-tracking control strategy programmed using LabVIEW FPGA in Compact RIO National Instrument (NI) hardware

Gender and Posture are Significant Risk Factors to Musculoskeletal Symptoms during Touchscreen Tablet Computer Use

[Purpose] To investigate the prevalence of neck and shoulder symptoms during the use of tablet computer, and to identify the risk factors associated with these symptoms. [Subjects and Methods] A cross-sectional survey was conducted to study tablet computer usage, posture during use, and neck and shoulder symptoms in 412 participants in a school setting. Significant risk factors for musculoskeletal symptoms during tablet computer use were identified. [Results] Overall prevalence of musculoskeletal symptoms during tablet computer use was 67.9% with greater prevalence of neck symptoms (neck: 84.6%; shoulder/upper extremity: 65.4%). Significant risk factors associated with symptoms during use were: current musculoskeletal symptoms, gender, roles, and postural factors including: sitting without back support, sitting with device in lap, and lying on the side and on the back during tablet computer use. A multivariate analysis further showed that the odds for females to have symptoms were 2.059 times higher than males. [Conclusion] The findings revealed that female gender and other postural factors were significantly associated with musculoskeletal symptoms during the use of tablet computer. Among all postural factors, sitting without back support was identified as the most important risk factor for having musculoskeletal symptom

Prevalence and Risk Factors for Neck and Shoulder Musculoskeletal Symptoms in Users of Touch-Screen Tablet Computers

Background and Purpose: Neck and upper extremity symptoms are common health complaints in the general population and cause a substantial financial burden to the health care system. Neck pain is known to be a multi factorial disorder, with head and spinal posture being one of the most important factors. Currently there is little evidence showing a relationship between touch-screen tablet computer usage and neck/upper extremity pathologies. However, it is fair to postulate that the incidence of neck/upper extremity pathologies is higher within touch-screen tablet computer users, considering how users maintain static postures while using the device. The primary purposes of the current study were to 1) investigate the prevalence of neck and shoulder symptoms and potential risk factors, 2) identify risk factors associated with symptoms during device use, especially in sitting postures. The secondary purpose was to investigate gender differences in device usage behavior, symptoms, and postural factors. Subjects: A cross-sectional survey study was conducted in a population of university students, staff, faculty, and alumni (N = 412). Methods and Results: Prevalence of symptoms during device use was 67.9 %. Most symptoms were reported in the neck (84.6%) and upper back/shoulder areas (65.4%). With sitting postures, significant symptoms during tablet use included sitting without back support (p= 0.016) and sitting with device in the lap (p= 0.002) based on Chi-square analyses. A multiple logistic regression analysis further demonstrated that female gender (p=0.004) and sitting in a chair without back support (p=0.006) are the predictors of experiencing symptoms during the use of tablets. For other general postures, the significant factors are lying on the side (p= 0.002) and lying on the back (p= 0.016) during tablet use. Furthermore, our results showed that 70.1% of the female respondents reported to have musculoskeletal symptoms during device usage, in comparison to 29.9% of the male respondents (p= 0.019). Additionally, women (75.7%) demonstrated significantly more symptoms at the upper back and shoulder regions than men (24.3%) (p = 0.014)

Shelf Seas Baroclinic Energy Loss: Pycnocline Mixing and Bottom Boundary Layer Dissipation

Observations of turbulent kinetic energy dissipation rate from a range of historical shelf seas data sets are viewed from the perspective of their forcing and dissipation mechanisms: barotropic to baroclinic tidal energy conversion, and pycnocline and bottom boundary layer (BBL) dissipation. The observations are placed in their geographical context using a high resolution numerical model (NEMO AMM60) in order to compute relevant maps of the forcing (conversion). We analyze, in total, 18 shear microstructure surveys undertaken over a 17 year period from 1996 to 2013 on the North West European shelf, consisting of 3,717 vertical profiles of shear microstructure: 2,013 from free falling profilers and 1,704 from underwater gliders. A robust positive relationship is found between model-derived barotropic to baroclinic conversion, and observed pycnocline integrated. A fitted power law relationship of approximately one-third is found, giving a simple new parameterization. We discuss reasons for this apparent power law and where the “missing” dissipation may be occurring. We conclude that internal wave related dissipation in the bottom boundary layer provides a robust explanation and is consistent with a commonly used fine-scale pycnocline dissipation parameterization

Dependence of ombrotrophic peat nitrogen on phosphorus and climate

Nitrogen (N) is a key, possibly limiting, nutrient in ombrotrophic peat ecosystems, and enrichment by pollutant N in atmospheric deposition (Ndep, g m-2 a-1) is of concern with regard to peatland damage. We collated data on the N content of surface (depth ≤ 25 cm, mean 15 cm) ombrotrophic peat (Nsp) for 215 sites in the UK and 62 other sites around the world, including boreal, temperate and tropical locations (wider global data), and found Nsp to range from 0.5 % to 4%. We examined the dependences of Nsp on surface peat phosphorus (P) content (Psp), mean annual precipitation (MAP), mean annual temperature (MAT) and Ndep. Linear regression on individual independent variables showed highly significant (p < 0.001) correlations of Nsp with Psp (r2 = 0.23) and MAP (r2 = 0.14), and significant (p < 0.01) but weaker correlations with MAT (r2 = 0.03) and Ndep (r2 = 0.03). A multiple regression model using log-transformed values explained 36% of the variance of the UK data, 84% of the variance of the wider global data, and 47% of the variance of the combined data, all with high significance (p < 0.001). In all three cases, most of the variance was explained by Psp and MAP, but in view of a positive correlation between MAP and MAT for many of the sites, a role for MAT in controlling Nsp cannot be ruled out. There is little evidence for an effect of Ndep on Nsp. The results point to a key role of P in N fixation, and thereby C fixation, in ombrotrophic peats

Impact and recovery of pH in marine sediments subject to a temporary carbon dioxide leak

© 2014 The Authors. Published by Elsevier Ltd. A possible effect of a carbon dioxide leak from an industrial sub-sea floor storage facility, utilised for Carbon Capture and Storage, is that escaping carbon dioxide gas will dissolve in sediment pore waters and reduce their pH. To quantify the scale and duration of such an impact, a novel, field scale experiment was conducted, whereby carbon dioxide gas was injected into unconsolidated sub-sea floor sediments for a sustained period of 37 days. During this time pore water pH in shallow sediment (5 mm depth) above the leak dropped \u3e0.8 unit, relative to a reference zone that was unaffected by the carbon dioxide. After the gas release was stopped, the pore water pH returned to normal background values within a three-week recovery period. Further, the total mass of carbon dioxide dissolved within the sediment pore fluids above the release zone was modelled by the difference in DIC between the reference and release zones. Results showed that between 14 and 63% of the carbon dioxide released during the experiment could remain in the dissolved phase within the sediment pore water

Aged riverine particulate organic carbon in four UK catchments

The riverine transport of particulate organic matter (POM) is a significant flux in the carbon cycle, and affects macronutrients and contaminants. We used radiocarbon to characterise POM in 9 rivers of four UK catchments (Avon, Conwy, Dee, Ribble) over a one-year period. High-discharge samples were collected on three or four occasions at each site. Suspended particulate matter (SPM) was obtained by centrifugation, and the samples were analysed for carbon isotopes. Concentrations of SPM and SPM organic carbon (OC) contents were also determined, and were found to have a significant negative correlation. For the 7 rivers draining predominantly rural catchments, PO14C values, expressed as percent modern carbon absolute (pMC), varied little among samplings at each site, and there was no significant difference in the average values among the sites. The overall average PO14C value for all 7 sites of 91.2 pMC corresponded to an average age of 680 14C years, but this value arises from the mixing of differently-aged components, and therefore significant amounts of organic matter older than the average value are present in the samples. Although topsoil erosion is probably the major source of the riverine POM, the average PO14C value is appreciably lower than topsoil values (which are typically 100 pMC). This is most likely explained by inputs of older subsoil OC from bank erosion, or the preferential loss of high-14C topsoil organic matter by mineralisation during riverine transport. The significantly lower average PO14C of samples from the River Calder (76.6 pMC), can be ascribed to components containing little or no radiocarbon, derived either from industrial sources or historical coal mining, and this effect is also seen in the River Ribble, downstream of its confluence with the Calder. At the global scale, the results significantly expand available information for PO14C in rivers draining catchments with low erosion rates

Integrated System Health Management (ISHM) Technology Demonstration Project Final Report

Integrated System Health Management (ISHM) is an essential capability that will be required to enable upcoming explorations mission systems such as the Crew Exploration Vehicle (CEV) and Crew Launch Vehicle (CLV), as well as NASA aeronautics missions. However, the lack of flight experience and available test platforms have held back the infusion by NASA Ames Research Center (ARC) and the Jet Propulsion Laboratory (JPL) of ISHM technologies into future space and aeronautical missions. To address this problem, a pioneer project was conceived to use a high-performance aircraft as a low-cost proxy to develop, mature, and verify the effectiveness of candidate ISHM technologies. Given the similarities between spacecraft and aircraft, an F/A-18 currently stationed at Dryden Flight Research Center (DFRC) was chosen as a suitable host platform for the test bed. This report describes how the test bed was conceived, how the technologies were integrated on to the aircraft, and how these technologies were matured during the project. It also describes the lessons learned during the project and a forward path for continued work

Vertical mixing alleviates autumnal oxygen deficiency in the central North Sea

There is an immediate need to better understand and monitor shelf sea dissolved oxygen (O2) concentrations. Here we use high-resolution glider observations of turbulence and O2 concentrations to directly estimate the vertical O2 flux into the bottom mixed layer (BML) immediately before the autumn breakdown of stratification in a seasonally stratified shelf sea. We present a novel method to resolve the oxycline across sharp gradients due to slow optode response time and optode positioning in a flow “shadow zone” on Slocum gliders. The vertical O2 flux to the low-O2 BML was found to be between 2.5 to 6.4 mmol m−2 d−1. Episodic intense mixing events were responsible for the majority (up to 90 %) of this oxygen supply despite making up 40 % of the observations. Without these intense mixing events, BML O2 concentrations would approach ecologically concerning levels by the end of the stratified period. Understanding the driving forces behind episodic mixing and how these may change under future climate scenarios and renewable energy infrastructure is key for monitoring shelf sea health