COVID-19 Personal Reflection

Personal reflection submitted by University of Maine Alumnus Paul Bishop Butler and Alumna Janet Bishop Butler during the COVID-19 Pandemic. The submission came via the University of Maine Alumni Association

Security-Informed Safety: Supporting Stakeholders with Codes of Practice

Codes of practice provide principles and guidance on how organizations can incorporate security considerations into their safety engineering lifecycle and become more security minded

Robust Method of Determining Microfacet BRDF Parameters in the Presence of Noise via Recursive Optimization

Accurate bidirectional reflectance distribution function (BRDF) models are essential for computer graphics and remote sensing performance. The popular microfacet class of BRDF models is geometric-optics-based and computationally inexpensive. Fitting microfacet models to scatterometry measurements is a common yet challenging requirement that can result in a model being fit as one of several unique local minima. Final model fit accuracy is therefore largely based on the quality of the initial parameter estimate. This makes for widely varying material parameter estimates and causes inconsistent performance comparisons across microfacet models, as will be shown with synthetic data. We proposed a recursive optimization method for accurate parameter determination. This method establishes an array of local minima best fits by initializing a fixed number of parameter conditions that span the parameter space. The identified solution associated with the best fit quality is extracted from the local array and stored as the relative global best fit. This method is first applied successfully to synthetic data, then it is applied to several materials and several illumination wavelengths. This method proves to reduce manual parameter adjustments, is equally weighted across incident angles, helps define parameter stability within a model, and consistently improves fit quality over the high-error local minimum best fit from lsqcurvefit by an average of 71%

Using an assurance case framework to develop security strategy and policies

Assurance cases have been developed to reason and communicate about the trustworthiness of systems. Recently we have also been using them to support the development of policy and to assess the impact of security issues on safety regulation. In the example we present in this paper, we worked with a safety regulator (anonymised as A Regulatory Organisation (ARO) in this paper) to investigate the impact of cyber-security on safety regulation

Broken-Symmetry Ground States of Halogen-Bridged Binuclear Metal Complexes

Based on a symmetry argument, we study ground states of what we call MMX-chain compounds, which are the new class of halogen-bridged metal complexes. Commensurate density-wave solutions of a relevant multi-band Peierls-Hubbard model are systematically revealed within the Hartree-Fock approximation. We numerically draw ground-state phase diagrams, where various novel density-wave states appear.Comment: 5 pages, 4 figures embedded, to appear in Phys. Lett.

Software fault-freeness and reliability predictions

Many software development practices aim at ensuring that software is correct, or fault-free. In safety critical applications, requirements are in terms of probabilities of certain behaviours, e.g. as associated to the Safety Integrity Levels of IEC 61508. The two forms of reasoning - about evidence of correctness and about probabilities of certain failures -are rarely brought together explicitly. The desirability of using claims of correctness has been argued by many authors, but not been taken up in practice. We address how to combine evidence concerning probability of failure together with evidence pertaining to likelihood of fault-freeness, in a Bayesian framework. We present novel results to make this approach practical, by guaranteeing reliability predictions that are conservative (err on the side of pessimism), despite the difficulty of stating prior probability distributions for reliability parameters. This approach seems suitable for practical application to assessment of certain classes of safety critical systems

Validating accelerometry estimates of energy expenditure across behaviours using heart rate data in a free-living seabird

Two main techniques have dominated the field of ecological energetics, the heart-rate and doubly labelled water methods. Although well established, they are not without their weaknesses, namely expense, intrusiveness and lack of temporal resolution. A new technique has been developed using accelerometers; it uses the Overall Dynamic Body Acceleration (ODBA) of an animal as a calibrated proxy for energy expenditure. This method provides high resolution data without the need for surgery. Significant relationships exist between rate of oxygen consumption (V̇o2) and ODBA in controlled conditions across a number of taxa; however, it is not known whether ODBA represents a robust proxy for energy expenditure consistently in all natural behaviours and there have been specific questions over its validity during diving, in diving endotherms. Here we simultaneously deployed accelerometers and heart rate loggers in a wild population of European shags (Phalacrocorax aristotelis). Existing calibration relationships were then used to make behaviour-specific estimates of energy expenditure for each of these two techniques. Compared against heart rate derived estimates the ODBA method predicts energy expenditure well during flight and diving behaviour, but overestimates the cost of resting behaviour. We then combine these two datasets to generate a new calibration relationship between ODBA and V̇o2 that accounts for this by being informed by heart rate derived estimates. Across behaviours we find a good relationship between ODBA and V̇o2. Within individual behaviours we find useable relationships between ODBA and V̇o2 for flight and resting, and a poor relationship during diving. The error associated with these new calibration relationships mostly originates from the previous heart rate calibration rather than the error associated with the ODBA method. The equations provide tools for understanding how energy constrains ecology across the complex behaviour of free-living diving birds

Groundwater Use and the Need for a State-Wide Groundwater Level Monitoring Network in South Carolina

2010 S.C. Water Resources Conference - Science and Policy Challenges for a Sustainable Futur

Maximum Running Speed of Captive Bar-Headed Geese Is Unaffected by Severe Hypoxia

While bar-headed geese are renowned for migration at high altitude over the Himalayas, previous work on captive birds suggested that these geese are unable to maintain rates of oxygen consumption while running in severely hypoxic conditions. To investigate this paradox, we re-examined the running performance and heart rates of bar-headed geese and barnacle geese (a low altitude species) during exercise in hypoxia. Bar-headed geese (n = 7) were able to run at maximum speeds (determined in normoxia) for 15 minutes in severe hypoxia (7% O2; simulating the hypoxia at 8500 m) with mean heart rates of 466±8 beats min�1. Barnacle geese (n = 10), on the other hand, were unable to complete similar trials in severe hypoxia and their mean heart rate (316 beats.min�1) was significantly lower than bar-headed geese. In bar-headed geese, partial pressures of oxygen and carbon dioxide in both arterial and mixed venous blood were significantly lower during hypoxia than normoxia, both at rest and while running. However, measurements of blood lactate in bar-headed geese suggested that anaerobic metabolism was not a major energy source during running in hypoxia. We combined these data with values taken from the literature to estimate (i) oxygen supply, using the Fick equation and (ii) oxygen demand using aerodynamic theory for bar-headed geese flying aerobically, and under their own power, at altitude. This analysis predicts that the maximum altitude at which geese can transport enough oxygen to fly without environmental assistance ranges from 6,800 m to 8,900 m altitude, depending on the parameters used in the model but that such flights should be rare

Resilience learning for water sector culture change

This is the author accepted manuscript. The final version is available from the European Water Association via the link in this recor