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  • 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.
  • US Port Connectivity and Ramifications for Maintenance of South Atlantic Division Ports

    Abstract: This study utilized automatic identification system (AIS) data to quantify vessel traffic patterns within a predominantly US port network from 1 January 2009 to 31 December 2020, with the methods validated using independent data sets collected between 1 January 2015 and 31 December 2019. The analysis focused on South Atlantic Division (SAD) ports. AIS-derived data characterized individual ports’ traffic and port-to-port connectivity for the network. With foreign vessel entrances and clearances (E&C) data, the AIS-reported vessel characteristics enabled calculation of ships’ physical volume, which was a reasonable proxy for tonnage at many SAD ports. The PageRank algorithm was then applied to port-to-port traffic, revealing how individual ports participate in cargo movement through the network. PageRank scores also provided insight into the maritime supply chain beyond traditional traffic metrics. For example, many East Coast SAD ports ranked higher by PageRank than by raw tonnage. Because of the supply chain implications of shared vessel traffic, PageRank scores can augment tonnage metrics when prioritizing channel and infrastructure maintenance. Vessel volume, port-to-port connectivity, and PageRank scores reveal maritime supply chain resilience by identifying alternative destinations for cargo bound for disrupted ports, robustness across supply chains, and the effects of seasonality and disruptions.
  • State-of-Practice on the Mechanical Properties of Metals for Armor-Plating

    Abstract: This report presents a review of quasi-static and dynamic properties of various iron, titanium, nickel, cobalt, and aluminum metals. The physical and mechanical properties of these materials are crucial for developing composite armoring systems vital for protecting critical bridges from terrorist attacks. When the wide range of properties these materials encompass is considered, it is possible to exploit the optimal properties of metal alloys though proper placement within the armoring system, governed by desired protective mechanism and environmental exposure conditions.
  • Fort Hunter Liggett: A History and Analysis

    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 located on California’s Central Coast within Monterey County. The fort has been used as a training facility for large-scale maneuvers and live-fire exercises since its establishment as a US Army training facility in 1941. The periods of significance for Criterion A are: from 1769 to 1833, relating to the founding and development of Mission San Antonio de Padua; from 1834 to 1923, relating to Euro-American land grants and ranchos; from 1923 to 1940, relating to Hearst’s purchase of the property and subsequent development; from 1940 to 1945, relating to the establishment of the Hunter Liggett Military Reservation (HLMR) and activities related to WWII; from 1959 to 1970, relating to the establishment and buildup of CDEC; and from 1975 to 1980, relating to HLMR’s redesignation as Fort Hunter Liggett and associated development. This report provides a comprehensive historic context for ranges, features, and buildings at Fort Hunter Liggett in support of Section 110 of the NHPA.
  • Evaluating a Multi-Panel Air Cathode Through Electrochemical and Biotic Tests

    Abstract: To scale up microbial fuel cells (MFCs), larger cathodes need to be developed that can use air directly, rather than dissolved oxygen, and have good electrochemical performance. A new type of cathode design was examined here that uses a “window-pane” approach with fifteen smaller cathodes welded to a single conductive metal sheet to maintain good electrical conductivity across the cathode with an increase in total area. Abiotic electrochemical tests were conducted to evaluate the impact of the cathode size (exposed areas of 7 cm², 33 cm², and 6200 cm²) on performance for all cathodes having the same active catalyst material. Increasing the size of the exposed area of the electrodes to the electrolyte from 7 cm² to 33 cm² (a single cathode panel) decreased the cathode potential by 5%, and a further increase in size to 6200 cm² using the multi-panel cathode reduced the electrode potential by 55% (at 0.6 A m⁻²), in a 50 mM phosphate buffer solution (PBS). In 85 L MFC tests with the largest cathode using wastewater as a fuel, the maximum power density based on polarization data was 0.083 ± 0.006Wm⁻² using 22 brush anodes to fully cover the cathode, and 0.061 ± 0.003Wm⁻² with 8 brush anodes (40% of cathode projected area) compared to 0.304 ± 0.009Wm⁻² obtained in the 28 mL MFC. Recovering power from large MFCs will therefore be challenging, but several approaches identified in this study can be pursued to maintain performance when increasing the size of the electrodes.
  • 2021 Guided Wave Inspection of California Department of Water Resources Tainter Gate Post-Tensioned Trunnion Anchor Rods: Oroville Dam

    Abstract: The Engineering and Test Branch within the Division of Operations and Maintenance of the California Department of Water Resources (DWR) and U.S. Army Corps of Engineers (USACE), Sacramento District, tasked the Sensor Integration Branch (SIB) at the Engineer Research and Development Center (ERDC) to perform nondestructive testing (NDT) on the trunnion anchor rods at Oroville Dam through the use of ultrasonic guided waves. This is the fourth year of this NDT. The results of the testing are presented along with qualitative analysis in determining whether a rod is intact or compromised. Analysis is based upon the expected results from other rods at the site, knowledge of rod response at other sites, data gathered from the trunnion rod research test bed at ERDC, and comparison to the previous year’s effort.
  • National Ordinary High Water Mark Field Delineation Manual for Rivers and Streams : Interim Version

    Abstract: The ordinary high water mark (OHWM) defines the lateral extent of nontidal aquatic features in the absence of adjacent wetlands in the United States. The federal regulatory definition of the OHWM, 33 CFR 328.3(c)(7), states the OHWM is “that line on the shore established by the fluctuations of water and indicated by physical characteristics such as [a] clear, natural line impressed on the bank, shelving, changes in the character of soil, destruction of terrestrial vegetation, the presence of litter and debris, or other appropriate means that consider the characteristics of the surrounding areas.” This is the first manual to present a methodology for nationwide identification and delineation of the OHWM. A two-page data sheet and field procedure outline a weight-of-evidence (WoE) methodology to organize and evaluate observations at stream sites. This manual presents a consistent, science-based method for delineating the OHWM in streams. It also describes regional differences and challenges in identifying the OHWM at sites disturbed by human-induced or natural changes and illustrates how to use remote data to structure field inquiries and interpret field evidence using the principles of fluvial science. The manual demonstrates that, in many landscape settings, the OHWM may be located near the bankfull elevation.
  • Helicopter Rotor Blade Planform Optimization Using Parametric Design and Multi-Objective Genetic Algorithm

    Abstract: In this paper, an automated framework is presented to perform helicopter rotor blade planform optimization. This framework contains three elements, Dakota, ParBlade, and RCAS. These elements are integrated into an environment control tool, Galaxy Simulation Builder, which is used to carry out the optimization. The main objective of this work is to conduct rotor performance design optimizations for forward flight and hover. The blade design variables manipulated by ParBlade are twist, sweep, and anhedral. The multi-objective genetic algorithm method is used in this study to search for the optimum blade design; the optimization objective is to minimize the rotor power required. Following design parameter substitution, ParBlade generates the modified blade shape and updates the rotor blade properties in the RCAS script before running RCAS. After the RCAS simulations are complete, the desired performance metrics (objectives and constraints) are extracted and returned to the Dakota optimizer. Demonstrative optimization case studies were conducted using a UH-60A main rotor as the base case. Rotor power in hover and forward flight, at advance ratio 𝜇𝜇 = 0.3, are used as objective functions. The results of this study show improvement in rotor power of 6.13% and 8.52% in hover and an advance ratio of 0.3, respectively. This configuration also yields greater reductions in rotor power for high advance ratios, e.g., 12.42% reduction at 𝜇𝜇 = 0.4.
  • 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.
  • 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.