28 Mar 2023

Exploration of Two Polymer Nanocomposite Structure-Property Relationships Facilitated by Molecular Dynamics Simulation and Multiscale Modeling

Abstract: Polyamide 6 (PA6) is a semi-crystalline thermoplastic used in many engineering applications due to good strength, stiffness, mechanical damping, wear/abrasion resistance, and excellent performance-to-cost ratio. In this report, two structure-property relationships were explored. First, carbon nanotubes (CNT) and graphene (G) were used as reinforcement molecules in simulated and experimentally prepared PA6 matrices to improve the overall mechanical properties. Molecular dynamics (MD) simulations with INTERFACE and reactive INTERFACE force fields (IFF and IFF-R) were used to predict bulk and Young's moduli of amorphous PA6-CNT/G nanocomposites as a function of CNT/G loading. The predicted values of Young's modulus agree moderately well with the experimental values. Second, the effect of crystallinity and crystal form (α/γ) on mechanical properties of semi-crystalline PA6 was investigated via a multiscale simulation approach. The National Aeronautics and Space Administration, Glenn Research Center's micromechanics software was used to facilitate the multiscale modeling. The inputs to the multiscale model were the elastic moduli of amorphous PA6 as predicted via MD and calculated stiffness matrices from the literature of the PA6 α and γ crystal forms. The predicted Young's and shear moduli compared well with experiment.

21 Mar 2023

An Ontology for an Epigenetics Approach to Prognostics and Health Management

Abstract: Techniques in prognostics and health management have advanced considerably in the last few decades, enabled by breakthroughs in computational methods and supporting technologies. These predictive models, whether data-driven or physics-based, target the modeling of a system’s aggregate performance. As such, they generalize assumptions about the modelled system’s components, and are thus limited in their ability to represent individual components and the dynamic environmental factors that affect composite system health. To address this deficiency, we have developed an epigenetics-inspired knowledge representation for engineered system state that encompasses components and environmental factors. Epigenetics is concerned with explaining how environmental factors affect the expression of an organism’s genetic material. The field has derived important insights into the development and progression of disease states based on how environmental factors impact genetic material, causing variations in how a gene is expressed. The health of an engineered system is similarly influenced by its environment. A foundation for a new approach to prognostics based on epigenetics must begin by representing the entities and relationships of an engineered system from the perspective of epigenetics. This paper presents an ontology for an epigenetics-inspired representation of an engineered system. An ontology describing the epigenetics of an engineered system will enable the composition of a formal model and the incremental development of a more robust, causal reasoning system.

13 Mar 2023

Safe and Rapid Development of Advanced Materials: A Research Case Study for Safe Development of Nanoenabled Environmental Sensors

Abstract: The enhanced understanding of nanomaterials properties and processing has led to increased use of nanotechnologies, which has also led to greater scrutiny on the commercialization and acquisition of emerging nanoenabled technologies. Caused by knowledge gaps on the unique behaviors, risks, and liabilities of novel engineered nanomaterials, this caution, when not evidence based, slows production and stifles innovation. Reducing the uncertainty surrounding the environmental risks and benefits of nanoenabled technologies, including their resilience in harsh environments, will speed the development and transition of advanced material technologies. In this work, a multifaceted research program generated data and processes to reduce that environmental uncertainty. Specifically, this case study examined printed, nanoenabled environmental sensors and their components to develop toxicological data and parameterize a life-cycle assessment. The study tested the sensors’ resilience in environmental weathering studies that considered both the potential release of the ingredient nanomaterials and the performance of the sensors after exposure to several harsh environmental climates and then created life-cycle inventories to determine environmental impact and reduce cost of research and development. Finally, this case study developed software tools to mitigate the cost of research and provide a framework for presenting toxicology data.

16 Feb 2023

Estimating Present Value Cost of Invasive Emerald Ash Borer (Agrilus planipennis) on USACE Project Lands

PURPOSE: The US Army Corps of Engineers (USACE) is responsible for stewardship of approximately 12.5 million acres across the United States. USACE’s Environmental Stewardship program mission is to protect, preserve, and restore significant ecological resources on USACE project lands. Since the early 2000s, non-native and invasive Emerald Ash Borer (EAB) has killed hundreds of millions of ash trees in the US, becoming the most destructive and costly invasive forest insect in North America. This research effort estimates the cost of managing EAB damage to USACE projects including treatment, removal, or removal and replacement of dying/dead ash trees. The results suggest potential impact to more than 122,800 USACE project acres in currently infested counties including 181,000 ash trees. While not all damaged trees require removal, many USACE recreation sites have ash trees that pose an increased risk to humans and structures thus requiring removal of EAB infected trees. The widespread and pervasive impacts of EAB will have significant costs associated with removal and replacement of ash trees that could be hazardous to recreational users at the projects. Data from the United States Department of Agriculture (USDA), Forest Inventory and Analysis (FIA) database, and methods developed by Kovacs et al. (2010) were utilized to calculate yearly present value costs of EAB to USACE projects from 2006-2026. Overall EAB impacts are estimated at $121.6 million across 201 USACE projects evaluated in this study. Increased efforts to limit EAB spread and perform measures of control are warranted to reduce potential cost to USACE.

7 Feb 2023

Remote Sensing Tools to Support Ordinary High Water Mark Delineation

Abstract: This document is a technical note (TN) that describes existing and recently developed tools to support ordinary high water mark (OHWM) identification and delineation. It also presents a case study to demonstrate how utilizing the tools provide supporting lines of evidence in OHWM delineations.

24 Jan 2023

Swan Island Resilience Model Development; Phase I: Conceptual Model

Abstract: This report documents the development of an integrated hydrodynamic and ecological model to test assumptions about island resilience. Swan Island, a 25-acre island in Chesapeake Bay, Maryland, was used as a case study. An interagency, interdisciplinary team of scientists and engineers came together in a series of workshops to develop a simplified resilience model to examine the ability of islands to reduce waves and erosion and the impacts to nearby habitats and shorelines. This report describes the model development process and the results from this first key step: model conceptualization. The final conceptual model identifies four main components: vegetative biomass, island elevation, waves/currents, and sediment supply. These components interact to form and support specific habitat types occurring on the island: coastal dunes, high marsh, low marsh, and submerged aquatic vegetation. The pre-and post-construction field data, coupled with hydrodynamic ecological models, will provide predictive capabilities of island resilience and evaluations of accrued benefits for future island creation and restoration projects. The process and methods described can be applied to island projects in a variety of regions and geographic scales.

10 Jan 2023

Strength and Toughness Inputs to Fitness for Service Analysis of Existing Hydraulic Steel Structures

Abstract: The purpose of this effort is to describe a database containing information about the strength and toughness of steel used in existing hydraulic steel structures (HSS). The lack of information about these properties often presents a barrier to conducting fitness for service (FFS) analysis. The statistical dependence between strength and toughness variables and other database fields is evaluated to assess their potential as predictive variables.

9 Dec 2022

Demonstration of an Autonomous Sailing Vessel for Monitoring Nearshore and Offshore Marine Environments

Abstract: This technical note describes the US Army Engineer Research and Development Center (ERDC) application of an autonomous sailing vessel (ASV) to monitor water quality near underwater unexploded ordnance in Vieques, Puerto Rico, and the Center for Acoustics Research and Education, University of New Hampshire, application of the ASV to monitor the ocean soundscape along the Atlantic Outer Continental Shelf.

9 Dec 2022

Invasive Species Costs to the USACE Navigation Business Line: A Demonstration Analysis in the Chicago District

Abstract: Executive Order 13112 requires federal agencies to report invasive species costs to the National Invasive Species Counsel (NISC) annually. NISC then reports to Congress to increase awareness of invasive species and encourage inter-agency cooperation. Since 2005, the US Army Corps of Engineers (USACE) has provided an annual estimate for the Civil Works (CW) business lines. Traditionally, USACE estimates have been informed by broad assumptions, as many invasive species costs are not itemized. This study sought to develop a method to improve these estimates. A demonstration analysis was conducted for the Chicago District Navigation Business Line and was used to inform recommendations for a nation-wide analysis. The demonstration revealed invasive species-related costs represent about 0.2% ($64,000) of the district’s Navigation Business Line. Invasive species costs are subject to many variables, such as the type, prevalence, and impact of invasive species, as well as the number and type of navigation projects. The Chicago District results are not presumed to be indicative of other districts’ invasive species costs. Rather, the demonstration informed the development of an invasive species cost estimating method that can adapted for each CW business line, as well as variations in invasive species and projects across geographic regions. This report describes the demonstration analysis and presents a defensible framework for quantifying the costs of invasive species to the USACE CW program.

6 Oct 2022

Incorporating Social and Environmental Outputs in Decision-Making: Workshop Outcomes

PURPOSE: This document summarizes the notable outcomes of the workshop “Quantifying and Incorporating Social and Environmental Outputs in Decision-Making—Research and Development Needs and Strategy Workshop.” The workshop was held 24 and 25 July 2019 in Alexandria, Virginia, at the US Army Corps of Engineers’ (USACE) Institute for Water Resources (IWR). The workshop sought to identify gaps in knowledge, methods, data, and tools and to identify types of subject matter experts who would be needed for the research team. A total of 22 participants attended the facilitated workshop, representing a broad array of expertise: economists, scientists, planners, social scientists, project managers, and researchers from a number of USACE organizations and partnering academics across the United States. Together, these attendees reviewed existing policy and research and prioritized future work to fill gaps in methods and procedures for incorporating social and environmental inputs across a broad range of USACE projects.