22 Apr 2021

Computational Investigation on Interactions between Some Munition Compounds and Humic Substances

Note: This document was originally published as a journal article or conference proceeding. The link and document will be accessible after a 12-month embargo expires (December 14, 2021 for this document). For more information, see "Frequently Asked Questions on Public Access to Federally Funded Journal Articles" at https://discover.dtic.mil/pdfs/padf/DTIC_FAQs_Public_Access.pdf Abstract: Humic acid substances (HAs) in natural soil and sediment environments affect the retention and degradation of insensitive munition compounds and legacy high explosives (MCs): 2,4-dinitroanisole (DNAN) DNi−NH4+, N-methyl-p-nitroaniline (nMNA), 1-nitroguanidine (NQ), 3-nitro-1,2,4-triazol-5-one (NTO; neutral and anionic forms), 2,4,6-trinitroto-luene (TNT), and 1,3,5-trinitro-1,3,5-triazinane (RDX). A humic acid mode compound has been considered using molecular dynamics, thermodynamic integration, and density functional theory to characterize the munition binding ability, ionization potential, and electron affinity compared to that in the water solution. Humic acids bind most compounds and act as both a sink and source for electrons. Ionization potentials suggest that HAs are more susceptible to oxidation than the MCs studied. The electron affinity of HAs is very conformation-dependent and spans the same range as the munition compounds. When HAs and MCs are complexed, the HAs tend to radicalize first, thus buffering MCs against reductive as well as oxidative attacks.

22 Apr 2021

guiBathy: A Graphical User Interface to Estimate Nearshore Bathymetry from Hovering Unmanned Aerial System Imagery

Abstract: This US Army Engineer Research and Development Center, Coastal and Hydraulics Laboratory, technical report details guiBathy, a graphical user interface to estimate nearshore bathymetry from imagery collected via a hovering Unmanned Aerial System (UAS). guiBathy provides an end-to-end solution for non-subject-matter-experts to utilize commercial-off-the-shelf UAS to collect quantitative imagery of the nearshore by packaging robust photogrammetric and signal-processing algorithms into an easy-to-use software interface. This report begins by providing brief background on coastal imaging and the photogrammetry and bathymetric inversion algorithms guiBathy utilizes, as well as UAS data collection requirements. The report then describes guiBathy software specifications, features, and workflow. Example guiBathy applications conclude the report with UAS bathymetry measurements taken during the 2020 Atlantic Hurricane Season, which compare favorably (root mean square error = 0.44 to 0.72 m; bias = -0.35 to -0.11 m) with in situ survey measurements. guiBathy is a standalone executable software for Windows 10 platforms and will be freely available at www.github.com/erdc.

22 Apr 2021

Comparison of Generic and Proprietary Aquatic Herbicides for Control of Invasive Vegetation : Part 2. Emergent Plants

Abstract: Aquatic herbicides are one of the most effective and widespread ways to manage nuisance vegetation in the US After the active ingredient is selected, often there are numerous proprietary and generic branded products to select from. To date, limited efforts have been made to compare the efficacy of brand name and generic herbicides head to head; therefore, at tot al of 20 mesocosm trials were conducted to evaluate various 2,4 -D, glyphosate, imazapyr, and triclopyr products against alligatorweed (Alternanthera philoxeroides (Mart.) Griseb.), southern cattail (hereafter referred to as cattail, Typha domingensis Pers.), and creeping water primrose (hereafter referred as primrose, Ludwigia peploides (Kunth) P.H. Raven). All active ingredients were applied to foliage at broadcast rates commonly used in applications to public waters. Proprietary and generic 2,4 -D, glyphosate, imazapyr, and triclopyr were efficacious and provided 39 to 99% control of alligatorweed, cattail and primrose in 19 of the 20 trials. There were no significant differences i n product performance except glyphosate vs. alligatorweed (trial 1, Rodeo vs. Roundup Custom) and glyphosate vs. cattail (trial 1, Rodeo vs. Glyphosate 5.4). These results demonstrate under small -scale conditions, the majority of the generic and proprietary herbicides provided similar control of emergent vegetation, regardless of active ingredient.

22 Apr 2021

Rapid Airfield Damage Recovery Next Generation Backfill Technologies Comparison Experiment : Technology Comparison Experiment

Abstract: The Rapid Airfield Damage Recovery (RADR) Next Generation Backfill Technology Comparison Experiment was conducted in July 2017 at the East Campus of the U.S. Army Engineer Research and Development Center (ERDC), located in Vicksburg, MS. The experiment evaluated three different crater backfill technologies to compare their performance and develop a technology trade-off analysis. The RADR next generation backfill technologies were compared to the current RADR standard backfill method of flowable fill. Results from this experiment provided useful information on technology rankings and trade-offs. This effort resulted in successful crater backfill solutions that were recommended for further end user evaluation.

22 Apr 2021

Automated Construction of Expeditionary Structures (ACES): Energy Modeling

Abstract: The need to conduct complex operations over time results in U.S. forces remaining in deployed locations for long periods. In such cases, more sustainable facilities are required to better accommodate and protect forward deployed forces. Current efforts to develop safer, more sustainable operating facilities for contingency bases involve construction activities that redesign the types and characteristics of the structures constructed, reduce the resources required to build, and reduce resources needed to operate and maintain the completed facilities. The Automated Construction of Expeditionary Structures (ACES) project was undertaken to develop the capability to “print” custom-designed expeditionary structures on demand, in the field, using locally available materials with the minimum number of personnel. This work investigated large-scale automated “additive construction” (i.e., 3D printing with concrete) for construction applications. This document, which documents ACES energy and modeling, is one of four technical reports, each of which details a major area of the ACES research project, its research processes, and associated results, including: System Requirements, Construction, and Performance; Energy and Modeling; Materials and Testing; Architectural and Structural Analysis.

22 Apr 2021

Estimating Bridge Reliability by Using Bayesian Networks

Abstract: As part of an inspection, bridge inspectors assign condition ratings to the main components of a bridge’s structural system and identify any defects that they observe. Condition ratings are necessarily somewhat subjective, as they are influenced by the experience of the inspectors. In the current work, procedures were developed for making inferences on the reliability of reinforced concrete girders with defects at both the cross section and the girder level. The Bayesian network (BN) tools constructed in this work use simple structural mechanics to model the capacity of girders. By using expert elicitation, defects observed during inspection are correlated with underlying deterioration mechanisms. By linking these deterioration mechanisms with reductions in mechanical properties, inferences on the reliability of a bridge can be made based on visual observation of defects. With more development, this BN tool can be used to compare conditions of bridges relative to one another and aid in the prioritization of repairs. However, an extensive survey of bridges affected by deterioration mechanisms is needed to confidently establish valid relationships between deterioration severity and mechanical properties.