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.

20 Mar 2023

Numerical Modeling of Supercritical Flow in the Los Angeles River: Part I: Adaptive Hydraulics Numerical Modeling of the 1943 Physical Model

Abstract: The Los Angeles District of the US Army Corps of Engineers is assisting the City of Los Angeles with restoration efforts on the Los Angeles River. The city wishes to restore portions of the channelized river to a more natural state with riparian/vegetative green spaces for both wildlife and public recreation usage. The Los Angeles River provides an important role for the City of Los Angeles from a flood-control perspective, and functionality needs to be preserved when contemplating system modifications. This report details the development of an Adaptive Hydraulics (AdH) numerical model capable of representing this complex system consisting of both subcritical and supercritical flow regimes. Due to limited hydraulic data in the study area, an extensive model validation to observed data was not possible. To bridge the data gap, a numerical model was developed from a previously completed physical model study with extensive quantitative measurements and qualitative reports of hydraulic conditions. This approach allowed engineers to evaluate the effectiveness of the AdH model in representing this complex hydraulic system along with determining the best methodology to accurately represent the existing conditions. This study determined appropriate model parameters that will be utilized in further numerical modeling efforts to evaluate system modifications associated with restoration efforts.

20 Mar 2023

Old River Control Complex (ORCC) Low Sill: A Literature Synthesis

Abstract: The US Army Corps of Engineers (USACE), New Orleans District (MVN), tasked the US Army Engineer and Research Development Center (ERDC) with assessing the condition of a grouted scour hole located at the southeast wall of the Old River Low Sill Structure (ORLSS) at the Old River Control Complex (ORCC) using noninvasive techniques, such as geophysical surveys and physical models. This special report (SR) combines a scientific literature synthesis of previous research with further geologic interpretation as a first step in the overall task assigned by MVN. The results discussed in this SR will be used to inform the interpretation of geophysical surveys, construction of physical models, and input for the slope stability analyses.

15 Mar 2023

Underwater Carbon Fiber–Reinforced Polymer (CFRP)–Retrofitted Steel Hydraulic Structures (SHS) Fatigue Cracks

Purpose: Recent advances in the use of fiber-reinforced polymers (FRP) to retrofit steel structures subjected to fatigue cracks have shown to be a viable solution for increasing fatigue life in steel hydraulic structures (SHS). Although several studies have been conducted to evaluate the use of FRP for retrofitting metal alloys and the promising potential of such has been well-demonstrated, the application has never been implemented in underwater steel structures. This Coastal and Hydraulics Engineering Technical Note presents the implementation of FRP patches to repair fatigue cracks at Old Hickory Lock and Dam miter gate.

15 Mar 2023

Suggested Updates for the Inclusion of Guidance on Ultra-High Performance Concrete to USACE Engineering Manual 1110-2-2000, Standard Practice for Concrete for Civil Works Structures

Abstract: Ultra-high performance concrete (UHPC) is a relatively modern class of concrete with properties that include very high compressive strengths, increased tensile strengths, very low permeability, and superior durability compared to conventional, normal-strength concrete. As research of this material continues to progress, its applications under both military and civil works categories expand. However, mixture and structural design guidance using UHPC is limited, particularly in the United States. This special report provides an overview of UHPC as initial guidance for the US Army Corps of Engineers (USACE) so that the material may be more easily utilized in civil works infrastructure. The information contained in this report is based on years of experience researching and developing UHPC at the US Army Engineer Research and Development Center (ERDC) and is intended to be a basis for the incorporation of this material class into USACE Engineer Manual (EM) 1110-2-2000, Standard Practice for Concrete for Civil Works Structures, when it is next updated.