7 May 2026

Robust Error State Sage-Husa Adaptive Kalman Filter for UWB Localization

Abstract: Given the sensors’ path and interference mitigation capabilities, ultra-wideband (UWB)-based positioning systems have demonstrated high accuracy and reliability. This work aims to improve the Sage-Husa fuzzy adaptive filter (SHFAF) proposed in previous works by modifying the motion model to a 3-D ground-based differential drive robot using IMU and wheel encoder kinematic fused control inputs. In addition to the changed motion model kinematics, this article improved the positive definite constraint on P and R during dynamic estimations, thus making the filter more robust to outliers. An improvement to the computation and derivation of the fuzzy logic system for the SHFAF based on the adaptive neuro-fuzzy inference system (ANFIS) structure was developed, and training the fuzzy system using gradient descent was applied to improve the system’s accuracy. Experimental validation was conducted using real-world data from a Clearpath Jackal robot equipped with Qorvo UWB sensors and static nodes. Regarding localization accuracy, the proposed velocity-based SHFAF (VelSHFAF) system outperformed the previous SHFAF implementation by approximately 30%–25% across two test courses, demonstrating its enhanced performance and reliability.

7 May 2026

Surface Oxide Removal in Preparation for Controlled Liquid Metal Embrittlement

Abstract: During liquid metal embrittlement a liquid metal infiltrates grain boundaries of a compatible solid metal, interrupting the inter-grain bonds and weakening the metal. Ongoing research has proposed that this effect may be used to perform additive/subtractive hybrid machining to fabricate replacement components, using relatively simple equipment and low material and instrument costs. The gallium/aluminum pairing is of particular interest due to the usage of aluminum in a wide variety of structural and aerospace applications coupled with gallium’s nontoxicity and melting point just above room temperature, which facilitates storage and transport. To activate aluminum to gallium infiltration, the surface oxide formed on aluminum in atmosphere must first be removed simultaneously with a significant amount of bulk metal to promote flow control of the liquid metal. Three targeted techniques for oxide removal were tested and compared, specifically mechanical abrasion, chemical etching, and laser ablation. Mechanical abrasion is simple to implement but lower precision. Chemical etching requires significant prep work and cleanup but could operate on entire sheets of substrate simultaneously with proper masking. Although laser ablation requires the most complex instrumentation, it requires minimal prep work and provides the greatest precision, making it ideal for the manufacturing application under development here.

7 May 2026

Self Excited Hoisting Chain Tension Measurements for Dam Spillway Gates and Identification of Uneven Hoisting

Abstract: Tainter gates are critical components of inland navigation systems, as they regulate the flow of water through dams, enabling a navigable depth of waterway. A critical issue with Tainter gates arises when the gates are raised or lowered in a skewed, uneven fashion, which can cause redistribution of stresses and exacerbate fatigue damage. This uneven hoisting of the gate manifests itself as unequal tension in the chains that raise the gate. An opportunity to indirectly measure the tension in hoisting chains arose during field testing of a Tainter gate, where accelerometers were placed on easily accessible locations on the Tainter gate with the goal to perform a modal analysis of the gate. During operation, the hoisting chains of the tested gate would audibly pop, which was clearly identifiable in acceleration records and expected to be the response of the chains themselves, rather than the modal vibrations of the Tainter gate. To support the notion that the recorded vibrations represent the response of the chains, this paper explores the dynamics of the chains to develop the relationship between chain frequency and tension. The developed relationship is validated in a laboratory experiment of a chain cut from a Tainter gate where the natural frequency of the chain is measured for varying tension in the chain. The results of the study show that this approach can be used as a quick and inexpensive method to monitor for uneven hoisting on Tainter gates from easily accessible locations on the gate and with inexpensive sensors.

7 May 2026

Quantifying the Role of Vegetation on Urban Heat over Bengaluru, India

Abstract: The urban heat island (UHI) effect refers to how cities tend to be warmer than their non-urban surroundings, which increases the risk for heat-related illnesses and amplifies energy demands. Therefore, developing UHI mitigation strategies is crucial. Bengaluru, India has been rapidly urbanizing, but has yet to receive attention regarding potential UHI mitigation strategies. This work uses the Weather Research and Forecasting model with the single-layer urban canopy model to determine how UHI intensity changes in Bengaluru with perturbations of −10%, + 10%, + 20%, and + 30% in vegetation amount since recent work has shown that vegetation amount is the leading control of urban heat in Bengaluru. These perturbations illustrate how much the UHI could be amplified by near-depletion of vegetation or mitigated via realistic increases in vegetation. The simulations were investigated diurnally and during the dry and wet seasons. Results show that increases in vegetation were associated with a decrease in urban land surface temperature, an increase in the latent heat flux, and decreases in the sensible heat flux, and vice versa for a decrease in vegetation. Significant changes in UHI intensity usually occurred only when vegetation was increased by 20% or more. However, for the dry season nighttime, which exhibited the highest UHI intensity in the control run (1.70oC), the 10% increase in vegetation produced a significant decrease of − 0.19oC in UHI intensity, likely due to a shallow planetary boundary layer height. These results could have implications for mitigating urban heat, and reducing energy demands and public health risk in Bengaluru.

7 May 2026

Tribological Properties of Synthetic and Biosourced Lubricants Enhanced by Graphene and Its Derivatives: A Review

Abstract: This review explores the tribological properties of biosourced lubricants (biolubricants) enhanced by graphene (Gr) and its derivatives and hybrids. Friction and wear at mechanical interfaces are the primary causes of energy loss and machinery degradation, necessitating effective lubrication strategies. Traditional lubricants derived from mineral oils present environmental challenges, leading to an increased interest in biolubricants derived from plant oils and animal fats. Biolubricants offer high biodegradability, renewability, and low toxicity, positioning them as ecofriendly alternatives. This work extensively reviews the role of Gr-based nanoadditives in enhancing the lubrication properties of biolubricants. Gr with its exceptional physicomechanical properties has shown promise in reducing friction and wear. The review covers various Gr derivatives, including Gr oxide (GO) and reduced Gr oxide (r-GO), and their performance as lubrication additives. The discussion extends to Gr hybrids with metals, polymers, and other 2D materials, highlighting their synergistic effects on the tribological performance. The mechanisms through which these additives enhance lubrication, such as the formation of protective films and improved interactions between lubricants and tribopairs, are examined. Emphasis is placed on the environmental benefits and potential performance improvements of Gr-based biolubricants. Finally, by analyzing current research and technological trends, the paper outlines future prospects for optimizing lubricant formulations with Gr-based nanoadditives, aiming for more sustainable and efficient tribological applications.

7 May 2026

An All-Hazards Return on Investment (ROI) Model to Evaluate U.S. Army Installation Resilient Strategies

Abstract: The paper describes our project to develop, verify, and deploy an All-Hazards Return of Investment (ROI) model for the U.S. Army Engineer Research and Development Center (ERDC) to provide army installations with a decision support tool for evaluating strategies to make existing installation facilities more resilient. The need for increased resilience to extreme weather caused by climate change was required by U.S. code and DoD guidance, as well as an army strategic plan that stipulated an ROI model to evaluate relevant resilient strategies. During the project, the ERDC integrated the University of Arkansas designed model into a new army installation planning tool and expanded the scope to evaluate resilient options from climate to all hazards. Our methodology included research on policy, data sources, resilient options, and analytical techniques, along with stakeholder interviews and weekly meetings with installation planning tool developers. The ROI model uses standard risk analysis and engineering economics terms and analyzes potential installation hazards and resilient strategies using data in the installation planning tool. The ROI model calculates the expected net present cost without the resilient strategy, the expected net present cost with the resilient strategy, and ROI for each resilient strategy. The minimum viable product ROI model was formulated mathematically, coded in Python, verified using hazard scenarios, and provided to the ERDC for implementation.

6 May 2026

Two-Dimensional Thermal and Dynamical Strain in Landfast Sea Ice from InSAR: Results From a New Analytical Inverse Method and Field Observations

Abstract: Observing continuous strain in sea ice at geophysical scales of tens of meters to kilometers requires displacement measurements made with millimeter-scale precision. Satellite-based interferometric synthetic aperture radar (InSAR) provides such precise measurements of relative surface displacement over broad spatial areas at regular intervals and, unlike point displacement measurements, it allows confident delineation of continuously deforming regions. However, InSAR only captures the 1-D component of surface displacement parallel to a radar’s lines-of-sight. Additional analysis is required to translate between these 1-D observations and the horizontal or vertical displacements they arose from. Previous studies utilize an iterative inverse model to constrain estimates of horizontal surface displacement from InSAR. Here we build upon that work outlining a new analytical inverse modeling method for quantifying displacement and strain over continuous regions of sea ice and provide comparison between model results and independent displacement observations. We demonstrate the inverse method over both landfast and drifting ice along the Alaskan coastline. These intercomparisons highlight environments in which displacements inverted from interferograms may be used as an independent estimator of surface strain, as well as the potential for the outlined inverse methods to be used in conjunction with other observing methods.

6 May 2026

Economic Valuation and Natural Resource Damage Assessment Methods at Myakka River State Park, Florida

Abstract: The growing population and distribution of invasive wild pigs across vulnerable ecological communities has emerged as a significant issue, and there is not a standardized ecological-economic framework to precisely measure and value the impact of wild pigs to natural resources. The FY24 research presented here is year four of a 4-year research plan to develop a user-friendly ecological-economic framework for rapid assessment and valuation of wild pig damage to wetlands. Building off the findings from research conducted at Somerville Lake, Texas, and Richard K. Yancey Wildlife Management Area, Louisiana, this FY24 research took place at Myakka River State Park, Florida. Research objectives for FY24 included adapting the ecological-economic framework to a different landscape type, refining and broadening the artificial intelligence–based economic valuation approach by valuing a variety of natural communities, and improving the setup of the before-after-control-impact study design estimating damage reduction after a targeted control effort. Across the study area, we estimated that the benefits provided by the natural communities lost to wild pigs over a 1-year period were $273,525 (80% confidence interval: $72.684 and $920.883), and an aerial gunning control effort produced an estimated 685% return on investment in avoided losses 4 weeks postmanagement.

5 May 2026

Uptake and Elimination of Per-and Polyfluoroalkyl Substances in Earthworms Exposed to Spiked Artificial Soil or Aqueous Medium

Abstract: We investigated the accumulation of per-and polyfluoroalkyl substances (PFAS) in earthworms (Eisenia andrei). Uptake kinetics and bioaccumulation factors (BAFs) were determined using a mixture of 16 PFAS by exposing earthworms to spiked artificial soil for up to 28 days. Two treatments were used, with the low treatment targeting environmentally relevant concentrations. The concentrations of PFAS remained relatively unchanged during the exposures and statistically significant rates of uptake were estimated for most individual PFAS. For the 0.01 mg/kg treatment (target concentration of each PFAS), steady state was reached for all PFAS except perfluoroheptanoic acid, perfluorohexanesulfonic acid (PFHxS), perfluorooctanesulfonic acid (PFOS), perfluorotetradecanoic acid (PFTeDA), and perfluorotridecanoic acid. For the 0.01 mg/kg treatment, bioaccumulation factors (BAF; kg/kg-dry wt) ranged from 4–49 for most PFAS but were higher for PFHxS (72), PFTeDA (271), and perfluoroundecanoic acid (299). Organic carbon–normalized BAFs were within the range of published values. The BAF values increased with increasing length of the alkyl chain for perfluoroalkyl carboxylic acids (PFCAs), but not for perfluoroalkyl sulfonic acids (PFSAs). Uptake rates and BAFs were lower for the 1 mg/kg treatment, typically by over one order of magnitude, likely because of sublethal physiological impairment. Fast and steep decreases in tissue concentrations of PFAS occurred when earthworms were transferred to clean soil, even for long chain PFAS, agreeing overall with previous reports. However, measured elimination rates were faster than predicted from the uptake experiments and the causes remain unknown. Bioaccumulation of PFAS was also investigated in exposures to aqueous medium for up to 7 days to derive bioconcentration factors (BCFs). Comparison of BCFs and BAFs suggests that uptake from soil may have higher relevance than dermal uptake from porewater for long-chain PFCAs and PFSAs.

5 May 2026

Permafrost and Rain Influence Summer Hydrologic Flowpaths in Boreal Catchments

Abstract: Flowpaths of water through catchments influence water quality and flow regimes of streams. Depths of dominant flowpaths respond to variation in climate and catchment characteristics, such as topography, vegetation, and soil type. In high‐latitude regions, the depth and spatial extent of permafrost influences catchment hydrology, and thawing permafrost might change sources and pathways of water supplying solutes and flow to streams. We estimated contributions of precipitation, soil water, and groundwater flowpaths to streams during the open‐water period after snowmelt by applying a Bayesian mixing model to 4–6 years of observed solute concentrations in five catchments of boreal Alaska. The relative contribution of groundwater to streams varied from 12% to 82% across catchments and years and declined as spatial extent of permafrost increased from 25% to 58% across catchments, indicating potential for increased infiltration and drainage as permafrost thaws. Temporal patterns in precipitation also influenced flowpaths. The mean annual contribution of precipitation to streamflow increased in years with more rain. Groundwater contribution increased, on average, in years with few large storms, suggesting deepening flows due to seasonal ground thaw or loss of shallow water to evapotranspiration. In contrast, groundwater contributed less in years when large storms delivered most of the year's rain in late summer or autumn. Overall, spatial and temporal variation in relative flowpath contributions to streams suggest that permafrost thaw will deepen flowpaths, but increasing precipitation expected in high‐latitude regions under warming climate might obscure this effect by routing water via shallow flowpaths following large storms.