10 Sep 2025

Light Availability Calculator for Identifying Suitable Habitat for Light-Limited Aquatic Vegetation

Purpose: The purpose of this Ecosystem Management and Restoration Research Program Technical Note (EMRRP TN) is to introduce a geospatial Light Availability Calculator, designed to inform suitable habitat selection for light-limited, submerged aquatic vegetation (SAV) species. The need and intended use for the Light Availability Calculator is first described. Then, the scientific and mathematical formulations underpinning the calculator are explained. Finally, recommendations for calculator inputs reflective of various user needs (simple and rapid versus complex and time intensive) are described.

10 Sep 2025

Evaluation of the Plate Load Test for Design of Rigid Airfield Pavements Using Various Plate Sizes

Abstract: This report addresses the state of knowledge of the plate load test and modulus of subgrade reaction (k), industry’s desire to simplify the plate load test, and the effect of the k-value on rigid pavement design. The report traces back the theory behind the k-value over 150 years to evaluate the current state of knowledge. A total of 144 plate load tests were executed on three subgrade materials under varying base course thick-nesses. Plate load testing was designed to evaluate various plate sizes and testing standards (e.g., the military standard CRD-C 655-96 and the ASTM International [commonly called ASTM] standard ASTM D1196-21). By measuring plate load tests on varying base course thicknesses, field-measured effective k-curves were developed. Overall, results show that kASTM was higher than kCRD. Although a smaller plate setup produced similar results, additional variability was introduced when using smaller plates. The results of the field data imply that the current effective k-curves underestimate the global stiffness contribution provided by the base layer. Findings suggest the analytically generated effective k-curves validate the measured k-values in the field.

10 Sep 2025

Cellulose Nanofibers Impart Melt Resistance to Ice Through Optical and Thermal Mechanisms

Abstract: Ice is ubiquitous in cold regions with historical significance as a key structural material. Contemporary efforts to leverage ice for the construction of large structures have incorporated cellulose-based reinforcing materials to increase strength. While an increased resistance to melting has been observed, it has not been investigated. Herein, we provide evidence that cellulose nanofibers (CNFs), as a heterogeneous component to synthetic ices, increase melt resistance through optical and thermal mechanisms. Specifically, we investigated the effect of 0.1−1.0 wt % CNFs on the reflectance, thermal conductivity, and melt rate of ice. The presence of CNFs increased reflectance of ice from 20 to 70% at 640 nm. Thermophysical measurements revealed that CNFs both slow melting and facilitate freezing and do not statistically affect the specific heat capacity of ice. Measurements with light flash analysis revealed that CNFs reduce thermal conductivity up to 10%. Overall CNFs reduced the melt rate of ice by 10× with only 1.0 wt % CNF. These results demonstrate that insoluble CNFs impart melt resistance to ice by both optical and thermal mechanisms, results that provide an interesting combination of controls for ice stability and formation to optimize ice material properties for high performance applications in cold regions.

9 Sep 2025

Projecting the Longevity of Coastal Foredunes Under Stochastic Meteorological and Oceanographic Forcing

Abstract: Coastal foredunes serve as critical buffers between the ocean and beach-adjacent infrastructure, yet these features are at increasing risk of destruction from future storms and changes in sea level. Quantifying potential future hazards to dunes is complicated by an inability to forecast the exact sequencing and magnitude of future oceanographic and meteorological forcings. We used a stochastic weather emulator capable of generating time series of wind and wave properties to force a reduced complexity morphologic model to assess potential accretional and erosional dune volume changes over the next century. Inclusion of background beach erosion rates and sea level changes instead drives more frequent net volumetric dune erosion. At decadal scales, volume changes of the dune are shown to be dominated by the magnitude of shoreline change rate in locations rapidly retreating. For stable and mildly eroding shorelines, shoreline changes and changes in the still water level influence timescales of dune destruction. Sets of probabilistic simulations are used to show gradual wind-driven sediment gains can compensate for episodic wave-driven losses over the long term. However, in the case of higher sea levels, more frequent dune collision results in less time for dune recovery between major storms.

9 Sep 2025

Distinct Sandbar Behavior on a Gently Sloping Shoreface Sea-Breeze Dominated Beach

Abstract: Sandbars are common features in sandy nearshore environments that readily migrate in response to changing hydrodynamic conditions and can provide coastal protection by inducing wave breaking and through sediment feeding to the beach. A comprehensive 9-year data set of weekly to bi-weekly surveys of the beach and shallow nearshore, undertaken on an accretive micro-tidal sea-breeze dominated beach along the southeastern coast of Mexico, are presented here that shed new insights into hydrodynamic drivers of inner surf zone sandbar and shoreline dynamics. During spring-summer, short period waves drive offshore sandbar migration. Winter storms generate more energetic swell waves that induce onshore sandbar migration. Seasonal changes of shoreline and inner sandbar position are coupled, with on-shore sandbar migration being synchronous to seasonal shoreline advance, suggesting a gradual feeding of sediment from the bar system onto the beach. Analysis of the data are used to explore the physical drivers of sub-seasonal sandbar evolution at the site. The sandbar dynamics in the study area, showing an opposite behavior to conventional expectation of storm-induced offshore transport, are well correlated to seasonal changes of waves properties. This distinct sandbar behavior might be present at other gently sloping shoreface sea-breeze dominated sandy beaches.

9 Sep 2025

Active Layer and Permafrost Microbial Community Coalescence Increases Soil Activity and Diversity in Mixed Communities Compared to Permafrost Alone

Abstract: Permafrost is experiencing rapid degradation due to climate warming. Dispersal of microbial communities from the seasonally-thawed active layer soil into newly thawed permafrost may influence community assembly and increase carbon release from soils. We conducted a laboratory soil mixing study to understand how carbon utilization, heterotrophic respiration, and microbial community structure were affected when active layer and permafrost soils were mixed in varying proportions. Active layer soil and permafrost collected from two sites in Alaska were mixed in five different ratios and incubated for 100 days at 10°C. Respiration rates were highest in the 100% active layer soils, averaging 19.8 µg C-CO2 g−1 dry soil d−1 across both sites, and decreased linearly as the ratio of permafrost increased. Mixing of the two soil layers resulted in utilization of a more diverse group of carbon substrates compared to permafrost alone. Additionally, combining active layer and permafrost soils increased microbial diversity and resulted in communities resembling those from the active layer when soils were mixed in equal ratios. Understanding the effects of active layer-permafrost mixing on functional potential and soil organic matter decomposition will improve predictions of carbon-climate feedbacks as permafrost thaws in these regions.

9 Sep 2025

Bayesian Updating of Fatigue Crack Growth Parameters for Failure Prognosis of Miter Gates

Abstract: Navigable waterways play a vital role in efficient transportation of millions of tons of cargo annually. Inland traffic must pass through a lock, which consists of miter gates. Failures and closures of these gates can significantly disrupt waterborne commerce. Miter gates often experience fatigue cracking due to their loading and welded connections. Repairing every crack can lead to excessive miter gate downtime and serious economic impacts. If the rate of crack growth is shown to be sufficiently slow, immediate repairs may be deemed unnecessary, and this downtime can be avoided. Paris’ law is often obtained from laboratory testing with detailed crack measurements of specimens with relatively simple geometry. However, its parameters for an in situ structure will likely deviate from those predicted from physical testing due to variations in loading and materials and a more complicated geometry. To improve Paris’ law parameter prediction, we propose a framework that utilizes convenient vision-based tracking of crack evolution in the laboratory and the field and numerical model estimation of stress intensity factors. This study’s methodology provides an efficient tool for Paris’ law parameter prediction that can be updated as more data become available through vision-based monitoring and provide actionable information.

9 Sep 2025

Clustering to Inform Infrastructure Inspections

Abstract: Good inspections are crucial for managing risk and making decisions about facility maintenance. This paper proposes a method using the partitioning around medoids (PAM) algorithm to ensure that the inspector inspects a diverse set of components which maximize the information about the facility. We compares a number of different metrics by which to cluster the components using PAM, and evaluated the effectiveness of the clustering using Bayesian ANOVA testing.

9 Sep 2025

Using Transfer Learning to Enhance Void Detection and Shear Wave Velocity Model Inversion from Near-Surface Seismic Shot Gathers

Abstract: A Convolutional Neural Network (CNN) has been designed to delineate the shear-wave velocity (Vs) models and detect subsurface void locations. Addressing the processing and interpretation challenges posed on real seismic data, our strategy emphasizes that leveraging the ground truth, which is the void location in this study, enables the CNN to catch the identical features in real waveforms. Initially, a synthetic dataset is employed, imparting foundational knowledge to the CNN regarding the Vs model and void locations. Drawing inspiration from transfer learning, this pre-trained CNN serves as an initial model and is refined using a real dataset focused on void locations. After refining, the CNN shows enhanced reliability to detect the void and extract the Vs model, as evidenced by the improved alignment between forward modeling and real waveforms. Our findings underscore how leveraging the ground truth can actualize the potential of CNN on velocity model extraction.

9 Sep 2025

Damage Parameters and Crack Morphology in High Strength Concrete BBR9 Under Dynamic Uniaxial Compressive Loading: An Experimental Study

Abstract: There has been significant growth in the use of high-strength concrete in structures designed to withstand extreme events. Continuum damage mechanics has been utilized to develop constitutive models that can capture the damage evolution in concrete materials under such conditions. This study is aimed at investigating the damage initiation, progression, and morphology of HSC-Baseline Basic Research Mixture 9 when subjected to dynamic uniaxial compressive loading. A Kolsky compression bar system was implemented to introduce distinct damage states in the HSC-BBR9 specimens. The partially damaged specimens were tested to quantify their residual mechanical properties. Accordingly, stiffness-based and strength-based constitutive damage parameters were adopted to propose an indirect quantification of the damage state based on the deterioration of mechanical properties. The X-ray micro-computed tomography technique was utilized to extract measurements of 3D crack networks that provide a direct quantification of the damage state based on microstructural evidence. The results demonstrated the HSC-BBR9 material can maintain its residual mechanical properties into the post-peak regime. In the initial stages of damage, stiffness and strength deteriorate at a proportional rate; however, as damage accumulates, the rate of stiffness degradation increases. Correlations between constitutive damage parameters and 3D crack measurements were established.