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Archive: December, 2021
  • Assessing the Feasibility of Detecting Epileptic Seizures Using Non-Cerebral Sensor Data

    Abstract: This paper investigates the feasibility of using non-cerebral, time-series data to detect epileptic seizures. Data were recorded from fifteen patients (7 male, 5 female, 3 not noted, mean age 36.17 yrs), five of whom had a total of seven seizures. Patients were monitored in an inpatient setting using standard video-electroencephalography (vEEG), while also wearing sensors monitoring electrocardiography, electrodermal activity, electromyography, accelerometry, and audio signals (vocalizations). A systematic and detailed study was conducted to identify the sensors and the features derived from the non-cerebral sensors that contribute most significantly to separability of data acquired during seizures from non-seizure data. Post-processing of the data using linear discriminant analysis (LDA) shows that seizure data are strongly separable from non-seizure data based on features derived from the signals recorded. The mean area under the receiver operator characteristic (ROC) curve for each individual patient that experienced a seizure during data collection, calculated using LDA, was 0.9682. The features that contribute most significantly to seizure detection differ for each patient. The results show that a multimodal approach to seizure detection using the specified sensor suite is promising in detecting seizures with both sensitivity and specificity. Moreover, the study provides a means to quantify the contribution of each sensor and feature to separability. Development of a non-electroencephalography (EEG) based seizure detection device would give doctors a more accurate seizure count outside of the clinical setting, improving treatment and the quality of life of epilepsy patients.
  • Evaluation of Geocell-Reinforced Backfill for Airfield Pavement Repair

    Abstract: After an airfield has been attacked, temporary airfield pavement repairs should be accomplished quickly to restore flight operations. Often, the repairs are made with inadequate materials and insufficient manpower due to limited available resources. Legacy airfield damage repair (ADR) methods for repairing bomb damage consist of using bomb damage debris to fill the crater, followed by placement of crushed stone or rapid-setting flowable fill backfill with a foreign object debris (FOD) cover. While these backfill methods have provided successful results, they are heavily dependent on specific material and equipment resources that are not always readily available. Under emergency conditions, it is desirable to reduce the logistical burden while providing a suitable repair, especially in areas with weak subgrades. Geocells are cellular confinement systems of interconnected cells that can be used to reinforce geotechnical materials. The primary benefit of geocells is that lower quality backfill materials can be used instead of crushed stone to provide a temporary repair. This report summarizes a series of laboratory and field experiments performed to evaluate different geocell materials and geometries in combinations with a variety of soils to verify their effectiveness at supporting heavy aircraft loads. Results provide specific recommendations for using geocell technology for backfill reinforcement for emergency airfield repairs.
  • Semi-Automated Land Cover Mapping Using an Ensemble of Support Vector Machines with Moderate Resolution Imagery Integrated into a Custom Decision Support Tool

    Abstract: Land cover type is a fundamental remote sensing-derived variable for terrain analysis and environmental mapping applications. The currently available products are produced only for a single season or a specific year. Some of these products have a coarse resolution and quickly become outdated, as land cover type can undergo significant change over a short time period. In order to enable on-demand generation of timely and accurate land cover type products, we developed a sensor-agnostic framework leveraging pre-trained machine learning models. We also generated land cover models for Sentinel-2 (20m) and Landsat 8 imagery (30m) using either a single date of imagery or two dates of imagery for mapping land cover type. The two-date model includes 11 land cover type classes, whereas the single-date model contains 6 classes. The models’ overall accuracies were 84% (Sentinel-2 single date), 82% (Sentinel-2 two date), and 86% (Landsat 8 two date) across the continental United States. The three different models were built into an ArcGIS Pro Python toolbox to enable a semi-automated workflow for end users to generate their own land cover type maps on demand. The toolboxes were built using parallel processing and image-splitting techniques to enable faster computation and for use on less-powerful machines.
  • Field Jet Erosion Tests on Benbrook Dam, Texas

    Abstract: This report summarizes the results of eight field Jet Erosion Tests (JETs) performed on Benbrook Dam, TX. The results from these tests will be used by the U.S. Army Corps of Engineers, Fort Worth District, in assessments of the erosion resistance of the Benbrook Dam with regards to possible overtopping by extreme flooding. The JETs were performed at four different locations, i.e., two locations at the lowest crest elevation and two locations at the mid-slope face of the downstream embankment. Variations in estimated critical hydraulic shear stress and erosion rate values may have been caused by differences in soil composition, i.e., when the material changed from silt/sand to clay. The resulting values of the Erodibility Coefficient, Kd, and Critical Stress, τc, are very useful information in assessing the stability of Benbrook Dam during an overtopping event. Because of the observed natural variability of the materials, combining the erosion parameters presented in this report with the drilling logs and local geology will be imperative for assessing erosion-related failure modes of Benbrook Dam.
  • Development of a Sand Boil Testing Laboratory and Preliminary Results

    Purpose: To document the purpose, use, and preliminary results of a full-scale sand boil generator developed at the Geotechnical and Structures Laboratory.
  • Improving Winter Traction for Vehicles in Northern Operations

    Abstract: As part of the campaign to increase readiness in northern regions, a near commercial off-the-shelf (COTS) solution was identified for the High Mobility Multipurpose Wheeled Vehicle (HMMWV); and used to assess the suitability of commercially available winter tires for operational deployment. Initial performance evaluations conducted during the winters of 2020 and 2021 demonstrated and quantified significant improvements to traction and handling on a variety of winter surfaces. User feedback from United States Army Alaska (USARAK) Soldiers confirmed these results in an operational environment. Results of this study provide new winter tire specifications for the Army and justify the procurement of a HMMWV winter tire for improved safety and capability for US Soldier and vehicle fleet needs. The data and Soldier evaluations support attaining a National Stock Number (NSN) and provide data to develop models of winter vehicle performance that include the impact of winter tires and chains. This work also paves the way for future development and procurement of winter tires for vehicles where COTS solutions are unavailable. The motivation is to provide Soldiers with state-of-the-art winter tires to increase safety, capability, and operational compatibility with North Atlantic Treaty Organization (NATO) partners in the European Theater of Operations, and mobility superiority in all environments.
  • Data Collection Tools for River Geomorphology Studies: LiDAR and Traditional Methods

    Abstract: The purpose of this review is to highlight LiDAR data usage for geomorphic studies and compare to other remote sensing technologies. This review further identifies survey efficiencies and issues that can be problematic in using LiDAR digital elevation models (DEMs) in completing surveys and geomorphic analysis. US Army Corps of Engineers (USACE) geospatial data collection guidance (EM 1110-1-1000) (USACE 2015) aligns with the American Society for Photogrammetry and Remote Sensing Positional Accuracy Standards for Digital Geospatial Data (ASPRS 2014). Geomorphic assessment technologies are rapidly evolving, and LiDAR data collection methods are at the forefront. The FluvialGeomorph (FG) toolbox, developed to support USACE watershed planning, is a recent example of the use of LiDAR high-resolution terrain data to provide a new, efficient approach for rapid watershed assessments (Haring et al. 2020; Haring and Biedenharn 2021). However, there are advantages and disadvantages in using LiDAR data compared to other remote sensing technologies and traditional topographic field survey methods.
  • Sediment Transport Modeling at Stono Inlet and Adjacent Beaches, South Carolina

    Abstract: This report documents a numerical modeling investigation for dredged material from nearshore borrow areas and placed on Folly Beach adjacent to Stono Inlet, South Carolina. Historical and newly collected wave and hydrodynamic data around the inlet were assembled and analyzed. The datasets were used to calibrate and validate a coastal wave, hydrodynamic and sediment transport model, the Coastal Modeling System. Sediment transport and morphology changes within and around the immediate vicinity of the Stono Inlet estuarine system, including sand borrow areas and nearshore Folly Beach area, were evaluated. Results of model simulations show that sand removal in the borrow areas increases material backfilling, which is more significant in the nearshore than the offshore borrow areas. In the nearshore Folly Beach area, the dominant flow and sediment transport directions are from the northeast to the southwest. Net sediment gain occurs in the central and southwest sections while net sediment loss occurs in the northeast section of Folly Island. A storm and a 1-year simulation developed for the study produce a similar pattern of morphology changes, and erosion and deposition around the borrow areas and the nearshore Folly Beach area.
  • Development of Smartphone-Based Semi-Prepared Runway Operations (SPRO) Models and Methods

    Abstract: The U.S. Army Engineer Research and Development Center (ERDC) has developed a method for predicting surface friction response by use of ground vehicles equipped with deceleration-based measurement devices. Specifically, the ERDC has developed models and measurement methods between the Findlay Irvine Mk2 GripTester and a variety of deceleration measurement devices: Bowmonk AFM2 Mk3, Xsens MTi-G-710, two Android smartphones, and two iOS smartphones. These models show positive correlation between ground vehicle deceleration and fixed-slip surface continuous surface friction measurement. This effort extends prior work conducted by the U.S. Army ERDC in developing highly correlative models between the Findlay Irvine Mk2 GripTester and actual C-17 braking deceleration, measured via the runway condition rating (RCR) system. The models and measurement methods detailed here are of considerable use to semi-prepared airfield managers around the world needing to measure safe landing conditions following inclement weather. This work provides the tools necessary for airfield managers to quantify safe landing conditions for C-17 aircraft by using easily obtainable equipment and simple test standards.