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.

28 Mar 2023

Waste Management and Landfill Facilities Assessment Using Unmanned Aircraft Systems

Abstract: Finite and decreasing landfill space on Army installations is a significant concern. Efficient waste management is essential for achieving resiliency and extending the lifespan of remaining landfills. The purpose of this demonstration was to conduct independent performance tests of small unmanned aircraft systems (sUAS) and their utility for providing landfill assessments in remote areas where physical presence is either dangerous or inefficient. An active, near capacity construction and demolition (C&D) landfill at Fort Gordon, Georgia, was identified for the demonstration. The flights, data requirements, and outputs generated by the sUAS flyovers were analyzed for efficacy in detecting cell capacity and subsidence. Each flight took 1–2 hours for mobilization, ground marker placement, flight, and postflight analysis. Volumetric and topographic surveys were analyzed in less time than is typical for traditional surveying methods. After initial setup of ground markers and rectification, sUAS flights save a significant amount of time. However, skilled individuals are required for flights and for processing and maintaining data. The technology is widely relevant to the Army, is commercially available, and offers an average of 30% cost savings in terms of manpower, repeatability, and equipment. The use of sUAS technology is recommended for monitoring and surveying Army landfills.

27 Mar 2023

Evaluation of 11 Properties at Fort Hunter Liggett, California for Eligibility to the National Register

Abstract: The US Congress codified the National Historic Preservation Act of 1966 (NHPA), the nation’s most effective cultural resources legislation to date, mostly through establishing the National Register of Historic Places (NRHP). The NHPA requires federal agencies to address their cultural resources, which are defined as any prehistoric or historic district, site, building, structure, or object. Section 110 of the NHPA requires federal agencies to inventory and evaluate their cultural resources, and Section 106 requires them to determine the effect of federal undertakings on those potentially eligible for the NRHP. Fort Hunter Liggett is in Central California, entirely within Monterey County. It was first established as the Hunter Liggett Military Reservation in 1941. The post was renamed Fort Hunter Liggett in 1975. This report provides a determination of eligibility for nine properties (Buildings 172, 179, 196, 197, 291, 2199, 723, and 914 and facilities 0301BS and radio-controlled aerial target [RCAT]) constructed between 1956 and 1972 and recommends that none are eligible under the NRHP and the California Register of Historic Resources (CRHR) criteria. Two other properties (Buildings 177 and 178) were found to be covered by the Unaccompanied Personnel Housing (UPH) Program Comment of 2006. In consultation with the California State Historic Preservation Officer (CASHPO), this work fulfills Section 110 requirements for these buildings.

24 Mar 2023

Shallow Geothermal Technology, Opportunities in Cold Regions, and Related Data for Deployment at Fort Wainwright

ABSTRACT: The DoD considers improving Arctic capabilities critical (DoD 2019; HQDA 2021). Deployment of shallow geothermal energy systems at cold regions installations provides opportunity to increase thermal energy resilience by lessening dependence on fuel supply and supporting installations’ NetZero transitions. Deployment can be leveraged across facilities, for ex-ample using Fort Wainwright metrics for implementation of geothermal in cold region bases. Fort Wainwright is an extreme case of heating dominant loads owing to harsh conditions in Alaska, making it ideal for proving feasibility in most heating dominant installations. Proven feasibility and potential mass deployment will help reduce emissions and increase resilience across the DoD cold region network. This report introduces the shallow geothermal energy and storage technology combination that would best fit demonstration in Alaska. Focus is on leveraging shallow, low-temperature geothermal for the development of a larger geothermal district heating and cooling (GDHC) system with underground thermal energy storage (UTES) and geothermal heat exchangers (GHX). Such systems are proven in cooling dominant climates, and individual components are proven in heating dominant climates, but deployment of a larger system in a heating dominant climate is not well established. Deployment at Fort Wainwright would represent an improvement in the technology.

23 Mar 2023

Experimental Fatigue Evaluation of Underwater Steel Panels Retrofitted with Fiber Polymers

Abstract: Many steel structures are susceptible to fatigue loading and damage that potentially threaten their integrity. Steel hydraulic structures (SHS) experience fatigue loading during operation and exposure to harsh environmental conditions that can further reduce fatigue life through stress corrosion cracking and corrosion fatigue, for example. Dewatering to complete inspections or repairs to SHS is time consuming and leads to economic losses, and current repair methods, such as rewelding, often cause new cracks to form after relatively few cycles, requiring repeated inspection and repair. The use of bonded carbon fiber–reinforced polymer (CFRP) to repair fatigue cracks in metallic structures has been successful in other industries; recent work suggests that this method offers a more reliable repair method for SHS. Studies regarding CFRP retrofits of SHS indicate that early bond failure often controls the degree of fatigue life extension provided by the repair. This study aims to extend previous studies and increase the fatigue life of repaired steel components by employing methods to improve CFRP bonding. Additionally, using basalt reinforced polymer (BFRP) instead of CFRP is proposed. BFRP is attractive for SHS because it does not react galvanically and has excellent resistance to chemically active environments.

22 Mar 2023

MODIS Optical Global Water Intelligence (MOGWAI) Web Application User Guide

Abstract: Using the sensor from the Moderate Resolution Imaging Spectroradiometer (MODIS), the MODIS Optical Global WAter Intelligence (MOGWAI) platform is a system created and maintained jointly by the National Geospatial-Intelligence Agency and US Army Corps of Engineers (USACE) that monitors the surface area of lakes and reservoirs using remote sensing in near real time. MOGWAI provides estimates of surface area based on an implementation of the Dynamic Surface Water Extent algorithm that was adapted to use 8-day composites of surface reflectance data from the MODIS sensor, which belongs to the National Aeronautics and Space Administration (NASA). Surface area is monitored for all large waterbodies (greater than 10 km²)* south of 60°N contained in the HydroLAKES database. This information provides near real-time insights related to the regional buffering capacity against flood and drought.

21 Mar 2023

Characterization of Pigmented Microbial Isolates for Use in Material Applications

Abstract: Organisms (i.e., plants and microorganisms) contain pigments that allow them to adapt and thrive under stressful conditions, such as elevated ultraviolet radiation. The pigments elicit characteristic spectral responses when measured by active and passive sensors. This research study focused on characterizing the spectral response of three organisms and how they compared to background spectral signatures of a complex environment. Specifically, spectra were collected from a fungus, a plant, and two pigmented bacteria, one of which is an extremophile bacterium. The samples were measured using Fourier transform infrared spectroscopy and discriminated using chemometric means. A top-down examination of the spectral data revealed that organisms could be discriminated from one another through principal component analysis (PCA). Furthermore, there was a strong distinction between the plant and the pigmented microorganisms. Spectral differences resulting in samples with the highest variance from the natural background were identified using PCA loading plots. The outcome of this work is a spectral library of pigmented biological candidates for coatings applications.

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.

20 Mar 2023

Reception of Automatic Identification System (AIS) Message 21 from US Army Corps of Engineer AIS sites along the Upper Mississippi River, Mile 0 to 301

Purpose: The purpose of this study was to map the on-vessel receipt of message 21 broadcasts from shoreside Automatic Identification System (AIS) sites. Message 21 is one of 27 different AIS messages, and it is used to provide information about real and virtual aids to navigation (AtoNs). Virtual AtoNs are broadcast to warn mariners of hazards like temporary construction zones or submerged debris that may not be marked with a physical buoy. In this study, message 21 was broadcast from different shore-based AIS transceiver sites along the river. Equipment onboard the patrol vessel Pathfinder was monitored for receipt of message 21 during patrols on the Mississippi River that ranged from Lock and Dam (L&D) 22 to Cairo, Illinois, with the confluence of the Ohio River. The Pathfinder is owned by the US Army Corps of Engineers (USACE) and is based out of the St. Louis District (MVS). Understanding where vessels receive, or do not receive, message 21 has important implications for maritime safety in this heavily traveled portion of the inland waterway system.

20 Mar 2023

Hands-Free Mooring for Inland USACE Locks, Phase I: Technical Screening

Purpose: The US Army Corps of Engineers (USACE) Engineer Research and Development Center (ERDC) was asked to evaluate hands-free mooring (HFM) as an option for improving the safety and efficiency of lock operations at USACE locks within the United States. The focus of this research is assessing HFM solutions for barge tows on USACE inland waterway locks. This Coastal and Hydraulics engineering technical note (CHETN) describes the approach and findings from Phase I of this HFM research effort, which was funded through the Navigation Systems Research Program. Phase I includes defining the problem this research effort intends to address, understanding current mooring practices at USACE locks, gathering information on similar systems already in use, and developing design concepts and criteria.