Thermal Conductivity of Simulated Soils by the Needle Probe Method for Energy Foundation Applications

Soil thermal conductivity is an important parameter in the design of ground source heat pump and energy foundation systems. A laboratory method for measuring the soil thermal conductivity is the needle probe method. Earlier, analysis of the needle probe test data has been simplistic, relying heavily on human judgment and rules of thumb. This article presents an alternative method of analyzing the needle probe data with the aid of MATLAB, which is a technical programming language and computing environment. Four agar–kaolin specimens of varying densities were prepared to resemble simple soils. These were tested using the needle probe for a range of heating times and heating powers, to see what effect these parameters would have on the results. The repeatability when keeping the heating time and heating power constant was within ±2%. When the heating time and heating power were varied, the variation in results from the average for a given specimen ranged from ±4% to +10%/–8%. This range is significantly higher than the repeatability. Possible reasons for this are discussed in this article

Compact QED: the photon propagator, confinement and positivity violation for the pure gauge theory

The lattice Landau gauge photon propagator for the pure gauge theory is revisited using large lattices. For the confined case we show that it has an associated linearly growing potential, it has a mass gap, that is related to the presence of monopoles, and its spectral function violates positivity. In the deconfined phase, our simulations suggest that a free field theory is recovered in the thermodynamic limit.Comment: 7 pages, 6 figures, talk given at the XVth Quark confinement and the Hadron spectrum conference, August 1st - 6th, 2022, Stavanger, Norwa

Economics of geotechnical asset deterioration, maintenance and renewal

Transport and other infrastructure systems are supported on, adjacent to and retained by extensive systems of earthworks of varying (and increasing) age, and of variable original construction quality. These earthworks are subject to natural deterioration, which can be accelerated and complicated by the effects of climate change. The ACHILLES research program is providing improved understanding of earthworks behavior, performance and deterioration. It is also developing methods and tools to analyze and provide decision support for the construction, maintenance and renewal of earthworks, with particular emphasis on the management of existing, deteriorating assets. The work described here aims to identify the most cost-effective timing and means of extending earthworks asset lives and maintaining their safety and serviceability. Conventional cost-benefit analysis methods, of the type used for new infrastructure projects, do not directly provide the decision support needed for the maintenance and renewal of existing earthworks assets. An alternative approach is proposed and applied to a modeled example, demonstrating the potential asset management benefits of early, pre-emptive intervention, the economic attraction of deferred intervention, and the means of identifying an intermediate whole-life cost ‘sweet spot’, based on a timely assessment of intervention options. The handling of the uncertainty associated with earthworks behavior, deterioration rates and times to failure is also considered, as is the extension of the single-asset approach to the management of multiple earthworks assets

Unraveling the role of protein dynamics in dihydrofolate reductase catalysis

Protein dynamics have controversially been proposed to be at the heart of enzyme catalysis, but identification and analysis of dynamical effects in enzyme-catalyzed reactions have proved very challenging. Here, we tackle this question by comparing an enzyme with its heavy (15N, 13C, 2H substituted) counterpart, providing a subtle probe of dynamics. The crucial hydride transfer step of the reaction (the chemical step) occurs more slowly in the heavy enzyme. A combination of experimental results, quantum mechanics/molecular mechanics simulations, and theoretical analyses identify the origins of the observed differences in reactivity. The generally slightly slower reaction in the heavy enzyme reflects differences in environmental coupling to the hydride transfer step. Importantly, the barrier and contribution of quantum tunneling are not affected, indicating no significant role for “promoting motions” in driving tunneling or modulating the barrier. The chemical step is slower in the heavy enzyme because protein motions coupled to the reaction coordinate are slower. The fact that the heavy enzyme is only slightly less active than its light counterpart shows that protein dynamics have a small, but measurable, effect on the chemical reaction rate

Electrochemical evaluation and phase-related impedance studies on silicon–few layer graphene (FLG) composite electrode systems

Silicon-Few Layer Graphene (Si-FLG) composite electrodes are investigated using a scalable electrode manufacturing method. A comprehensive study on the electrochemical performance and the impedance response is measured using electrochemical impedance spectroscopy. The study demonstrates that the incorporation of few-layer graphene (FLG) results in significant improvement in terms of cyclability, electrode resistance and diffusion properties. Additionally, the diffusion impedance responses that occur during the phase changes in silicon is elucidated through Staircase Potentio Electrochemical Impedance Spectroscopy (SPEIS): a more comprehensive and straightforward approach than previous state-of-charge based diffusion studies

Reading Guide 6: The role of data analytics in decision-making.

Long linear infrastructure, e.g. highways and railways, includes large numbers of dispersed earthwork assets. Depending on their age and history, it can be practically impossible to constantly maintain up-to-date condition information. However, this data, and models using it, play a vital role in predicting earthwork behaviour and guiding intervention decision-making, which must take account of both the likelihood and consequences of asset failures. ACHILLES has developed novel surrogate models to help address uncertainty in earthwork assessment and make the most of limited data