King William County Shoreline Situation Report

The data inventory developed for the Shoreline Situation Reports are based on a three-tiered shoreline assessment approach. This assessment characterizes conditions in the shorezone observed from a small boat moving along the shoreline. Handheld GPS units record data observations in the field. The three tiered shoreline assessment approach divides the shorezone into three regions: the immediate riparian zone, evaluated for land use the bank, evaluated for height, stability and natural protection the shoreline, describing the presence of shoreline structures for shore protection and recreational purposes. Three GIS coverages are generated from the collection technique. The KW_lubc coverage are features related to the land use in the riparian zone, and conditions at the bank. The KW_sstru coverage includes information pertaining to structures for shoreline defense. Finally, KW_astru identifies structures which are typically built for access and recreational activities at the shore. They can be downloaded from this site through links at the bottom of this page. A metadata file is provided to describe each coverage. The GIS coverages use a digitized 1:24,000 scale USGS high water line (HWL) shoreline as the baseline coverage. However, if the position of the digitized HWL differs greatly from the observed shoreline on a 1994 color infra-red digital ortho quarter quadrangle (DOQQ), the shoreline position is corrected to align more closely with the land-water interface observed in the DOQQ. Using ArcInfo, the base shoreline is re-coded with the attributes defined in each coverage

Boron in copper: a perfect misfit in the bulk and cohesion enhancer at a grain boundary

Our ab initio study suggests that boron segregation to the Sigma 5(310)[001] grain boundary should strengthen the boundary up to 1.5 ML coverage (15.24 at/nm^2). The maximal effect is observed at 0.5 ML and corresponds to boron atoms filling exclusively grain boundary interstices. In copper bulk, B causes significant distortion both in interstitial and regular lattice sites for which boron atoms are either too big or too small. The distortion is compensated to large extent when the interstitial and substitutional boron combine together to form a strongly bound dumbell. Our prediction is that bound boron impurities should appear in sizable proportion if not dominate in most experimental conditions. A large discrepancy between calculated heats of solution and experimental terminal solubility of B in Cu is found, indicating either a sound failure of the local density approximation or, more likely, strongly overestimated solubility limits in the existing B-Cu phase diagram.Comment: 16 pages, 9 figure

Software engineering to sustain a high-performance computing scientific application: QMCPACK

We provide an overview of the software engineering efforts and their impact in QMCPACK, a production-level ab-initio Quantum Monte Carlo open-source code targeting high-performance computing (HPC) systems. Aspects included are: (i) strategic expansion of continuous integration (CI) targeting CPUs, using GitHub Actions runners, and NVIDIA and AMD GPUs in pre-exascale systems, using self-hosted hardware; (ii) incremental reduction of memory leaks using sanitizers, (iii) incorporation of Docker containers for CI and reproducibility, and (iv) refactoring efforts to improve maintainability, testing coverage, and memory lifetime management. We quantify the value of these improvements by providing metrics to illustrate the shift towards a predictive, rather than reactive, sustainable maintenance approach. Our goal, in documenting the impact of these efforts on QMCPACK, is to contribute to the body of knowledge on the importance of research software engineering (RSE) for the sustainability of community HPC codes and scientific discovery at scale.Comment: Accepted at the first US-RSE Conference, USRSE2023, https://us-rse.org/usrse23/, 8 pages, 3 figures, 4 table