10 Sep 2021

Variability in Weed Biological Control: Effects of Foliar Nitrogen on Larval Development and Dispersal of the Alligatorweed Flea Beetle, Agasicles hygrophila

Abstract: Host quality can have dramatic effects on performance of biological control agents but its importance is understudied. We used a combination of field measurements and laboratory experiments to determine the range of foliar nitrogen (FN) that larvae of the alligatorweed flea beetle (Agasicles hygrophila) are exposed to in the field and its importance to larval development and dispersal. Seasonal variability in FN was assessed at field sites spanning southern to northern Louisiana every 2–3 weeks during the growing season for four years. In a series of laboratory experiments, alligatorweed FN was manipulated to examine its influence on larval development and survival (under different temperature regimes), adult biomass, and dispersal of the biological control agent, A. hygrophila. Foliar nitrogen and rearing temperature had strong independent effects on larval development rate. We demonstrated that increasing nitrogen in leaf tissues shortens larval A. hygrophila developmental time and increases survival to adulthood, regardless of exposure temperature during development. It also suggests that foliar nitrogen may have important effects on biological control of alligatorweed, particularly as a result of seasonal variation in temperature and plant nutrition at field sites, and could contribute to observed variation in A. hygrophila efficacy in the field.

9 Sep 2021

Shear and Tensile Delamination of Ice from Surfaces: The Ice Adhesion Peel Test (IAPT)

ABSTRACT: For decades, researchers have sought to understand the adhesion of ice to surfaces so that low-cost ice mitigation strategies can be developed. Presently, the field of ice adhesion is still without formal standards for performing ice adhesion tests. The U.S. Army Corps Engineers’ Research and Development Center’s Cold Regions Research and Engineering Laboratory (ERDC-CRREL) has a longstanding history as an independent third party for ice adhesion testing services. Most notably, CRREL’s Zero-Degree Cone Test (ZDCT) has been an industry favorite for more than 30 years. Despite its wide acceptance, the ZDCT contains some shortcomings, namely that freshwater ice is formed on the surface of interest within the confines of an annular gap. To address this limitation, CRREL developed and uses the Ice Adhesion Peel Test (IAPT) for testing ice adhesion. This test employs an open planar substrate from which the ice can be removed under either tensile or shear loading, thereby allowing ice to be grown directly on the target substrate without the use of molds. The IAPT configuration is therefore amenable to different ice types and geometries and will provide utility to research studies that aim to develop surface treatments to mitigate ice in a wide range of environments. This report describes the IAPT and its use for characterizing the ice adhesion properties of materials.

9 Sep 2021

Mat Sinking Unit Supply Study: Mississippi River Revetment

Abstract: The Mississippi Valley Division (MVD) has maintained the Mississippi River banks for over 80 years. The Mat Sinking Unit (MSU), built in 1946, was considered state-of-the-art at the time. This system is still in operation today and has placed over 1,000 miles of Articulated Concrete Mats along the Mississippi River from Head of Passes, LA, to Cairo, IL. A new MSU has been designed and is expected to be fully mission capable and operational by the 2023 season, which is expected to increase the productivity from 2,000 squares/day up to 8,000 squares/day with double shifts and optimal conditions. This MSU supply study identifies and optimizes the supply chain logistics for increased production rates from the mat fields to the MSU. The production rates investigated for this effort are 2,000 squares/day, 4,000 squares/day, and 6,000 squares/day. RiskyProject® software, which utilizes a Monte Carlo method to determine a range of durations, manpower, and supplies based on logical sequencing is used for this study. The study identifies several potential supply and demand issues with the increased daily production rates. Distance to casting fields, number of barges, and square availability are the major issues to supply increased placement rates identified by this study.

9 Sep 2021

Geophysical Investigation to Assess Condition of Grouted Scour Hole: Old River Control Complex—Low Sill Concordia Parish, Louisiana

Abstract: Geophysical surveys, both land-based and water-borne, were conducted at the Old River Control Complex‒Low Sill, Concordia Parish, LA. The purpose of the surveys was to assess the condition of the grout within the scour region resulting from the 1973 flood event, including identification of potential voids within the grout. Information from the ground studies will also be used for calibration of subsequent marine geophysical data and used in stability analysis studies. The water-borne survey consisted of towed low frequency (16-80 MHz) ground penetrating radar (GPR), whereas the land-based surveys used electrical resistivity and seismic refraction. The GPR survey was conducted in the Old River Channel on the upstream side of the Low Sill structure. The high electrical conductivity of the water (~50 mS/m) precluded penetration of the GPR signal; thus, no useful data were obtained. The land-based surveys were performed on both northeast and southeast sides of the Low Sill structure. Both resistivity and seismic surveys identify a layered subsurface stratigraphy that corresponds, in general, with available borehole data and constructed geologic profiles. In addition, an anomalous area on the southeast side was identified that warrants future investigation and monitoring.

9 Sep 2021

Computational Mechanics of the Paddlefish Rostrum

Abstract: The rostrum of a paddlefish provides hydrodynamic stability during feeding process in addition to detect the food using receptors that are randomly distributed in the rostrum. The exterior tissue of the rostrum covers the cartilage that surrounds the bones forming interlocking star shaped bones. Design/methodology/approach – The aim of this work is to assess the mechanical behavior of four finite element models varying the type of formulation as follows: linear-reduced integration, linear-full integration, quadratic-reduced integration and quadratic-full integration. Also presented is the load transfer mechanisms of the bone structure of the rostrum. Findings – Conclusions are based on comparison among the four models. There is no significant difference between integration orders for similar type of elements. Quadratic-reduced integration formulation resulted in lower structural stiffness compared with linear formulation as seen by higher displacements and stresses than using linearly formulated elements. It is concluded that second-order elements with reduced integration and can model accurately stress concentrations and distributions without over stiffening their general response. Originality/value – The use of advanced computational mechanics techniques to analyze the complex geometry and components of the paddlefish rostrum provides a viable avenue to gain fundamental understanding of the proper finite element formulation needed to successfully obtain the system behavior and hot spot locations.

8 Sep 2021

Iterative Learning Algorithm for Records Analysis (ILARA) User Manual

Abstract: This manual is intended for new users with minimal or no experience with using the Iterative Learning Algorithm for Records Analysis (ILARA) tool. The goal of this document is to give an overview of the main functions of ILARA. The primary focus of this document is to demonstrate functionality. Every effort has been made to ensure this document is an accurate representation of the functionality of the ILARA tool. For additional information about this manual, contact ERDC.JAIC@erdc.dren.mil

8 Sep 2021

Data Documentation Tool (DDoT) User Manual

Abstract: This manual is intended for new users with minimal or no experience with using the Data Documentation Tool. The goal of this document is to give an overview of the main functions of DDoT. The primary focus of this doc-ument is to demonstrate functionality. Every effort has been made to ensure this document is an accurate repre-sentation of the functionality of the DDoT. For additional information about this manual, contact ERDC.JAIC@erdc.dren.mil

7 Sep 2021

A Bathymetric Study of the Forebay at the Old River Low Sill Structure from 1963 to 2019

Purpose: The purpose of this study is to use historical hydrographic surveys to quantify bathymetric changes in the forebay channel area of ORLSS over the last 56 yr. The results from this comparison support an ongoing geotechnical study led by Mr. Lucas Walshire, U.S. Engineer Research and Development Center (ERDC), for the U.S. Army Corps of Engineers, New Orleans District (USACE MVN).

7 Sep 2021

The Behaviour of Near-Surface Soils Through Ultrasonic Near-Surface Inundation Testing

Abstract: Seismometers installed within the upper metre of the subsurface can experience significant variability in signal propagation and attenuation properties of observed arrivals due to meteorological events. For example, during rain events, both the time and frequency representations of observed seismic waveforms can be significantly altered, complicating potential automatic signal processing efforts. Historically, a lack of laboratory equipment to explicitly investigate the effects of active inundation on seismic wave properties in the near surface prevented recreation of the observed phenomena in a controlled environment. Presented herein is a new flow chamber designed specifically for near-surface seismic wave/fluid flow interaction phenomenology research, the ultrasonic near-surface inundation testing device and new vp-saturation and vs-saturation relationships due to the effects of matric suction on the soil fabric.

7 Sep 2021

JAIC Predictive Maintenance Dashboard User Manual

Abstract: This manual is intended for new users with minimal or no experience with using the JAIC Predictive Maintenance Dashboard (JPD). The goal of this document is to give an overview of the main functions of JPD. The primary focus of this document is to demonstrate functionality. Every effort has been made to ensure this document is an accurate representation of the functionality of the JPD. For additional information about this manual, contact ERDC.JAIC@erdc.dren.mil