Copper Speciation in Wastewater-Impacted Surface Waters

This study investigates the relationship between total and ionic copper in samples taken from the Tualatin River and wastewater treatment facilities (WWTFs) that discharge into the Tualatin River. Copper speciation was analyzed by determining conditional stability constants and densities of copper binding ligands on the dissolved organic matter (DOM) in each sample using a two-ligand model. Differences in copper binding between wastewater and river water were identified, changes in copper binding following the mixing of WWTF effluent and receiving waters were observed, and the ability of the Biotic Ligand Model (BLM) to predict copper speciation in each sample was determined. WWTF effluent samples were found to bind copper more strongly than river water samples through a larger conditional stability constant for the strong binding site. At low dilution ratios, copper binding characteristics in waters downstream of WWTF outfalls deviated from those of upstream waters by approaching the WWTF effluent characteristics for copper binding. The BLM adequately predicted copper speciation in waters without a high percentage of WWTF effluent, but overpredicted ionic copper concentrations in effluent and downstream waters during low-flow by as much as 2-3 orders of magnitude. The differences observed highlight the need to account for WWTF DOM in the BLM framework

Identification of atypical flight patterns

Method and system for analyzing aircraft data, including multiple selected flight parameters for a selected phase of a selected flight, and for determining when the selected phase of the selected flight is atypical, when compared with corresponding data for the same phase for other similar flights. A flight signature is computed using continuous-valued and discrete-valued flight parameters for the selected flight parameters and is optionally compared with a statistical distribution of other observed flight signatures, yielding atypicality scores for the same phase for other similar flights. A cluster analysis is optionally applied to the flight signatures to define an optimal collection of clusters. A level of atypicality for a selected flight is estimated, based upon an index associated with the cluster analysis

Information Display System for Atypical Flight Phase

Method and system for displaying information on one or more aircraft flights, where at least one flight is determined to have at least one atypical flight phase according to specified criteria. A flight parameter trace for an atypical phase is displayed and compared graphically with a group of traces, for the corresponding flight phase and corresponding flight parameter, for flights that do not manifest atypicality in that phase

Reconstruction of former glacier surface topography from archive oblique aerial images

Archive oblique aerial imagery offers the potential to reconstruct the former geometry of valley glaciers and other landscape surfaces. Whilst the use of Structure-from-Motion (SfM) photogrammetry with multiview stereopsis (MVS) to process small-format imagery is now well established in the geosciences, the potential of the technique for extracting topographic data from archive oblique aerial imagery is unclear. Here, SfM-MVS is used to reconstruct the former topography of two high-Arctic glaciers (Midtre and Austre Lovénbreen, Svalbard, Norway) using three archive oblique aerial images obtained by the Norwegian Polar Institute in 1936. The 1936 point cloud was produced using seven LiDAR-derived ground control points located on stable surfaces in proximity to the former piedmont glacier termini. To assess accuracy, the 1936 data set was compared to a LiDAR data set using the M3C2 algorithm to calculate cloud-to-cloud differences. For stable areas (such as nonglacial surfaces), vertical differences were detected between the two point clouds (RMS M3C2 vertical difference of 8.5 m), with the outwash zones adjacent to the assessed glacier termini showing less extensive vertical discrepancies (94% of M3C2 vertical differences between ±5 m). This research highlights that historical glacier surface topography can be extracted from archive oblique aerial imagery, but accuracy is limited by issues including the lack of camera calibration, the quality and resolution of the archive imagery, and by the identification of suitable ground control. To demonstrate the value of historical glacier surfaces produced using oblique archive imagery, the reconstructed glacier surface topography is used to investigate evidence of a potential former surge front at the high-Arctic valley glacier, Austre Lovénbreen - a glacier identified to have potentially exhibited surge-type behaviour during the Neoglacial. A surface bulge of ~15–20 m is resolved on the 1936 model; however, when compared with the now deglaciated former subglacial topography, a surge origin for the surface feature becomes unclear. The processed 1936 oblique imagery was also used to produce orthorectified nadir aerial imagery, from which structural mapping was undertaken: this adds to the existing 1948–1995 structural map series for these glaciers. This research demonstrates the potential of SfM-MVS for reconstructing historical glacier surfaces, which is important for aiding our understanding of former glacier dynamics and enabling the rapid assessment of glacier change over time

Influence of Sn on Deformation Mechanisms During Room Temperature Compression of Binary Zr–Sn Alloys

Role of Sn on the deformation mechanisms of Zr was investigated undertaking in situ compression loading experiments using neutron diffraction and complementary post mortem electron microscopy. Fully recrystallised binary Zr–Sn alloys, displaying a typical rolling + recrystallisation texture, were studied in situ to determine intergranular strain development, monitor peak intensity changes indicative of twinning, and peak broadening indicative of increased dislocation density. Significant { 101¯2 } 〈 101¯1 〉 type tensile twinning activity was observed for all samples during compression loading. The critical stress for the twin nucleation and the extent of twinning were found to be strongly influenced by the Sn content. Critical plastic strain for the nucleation of twining, however, was observed to be weakly dependent on the Sn content. Results demonstrate significant plastic slip activity to be a necessary condition for the onset of twinning regardless of the Sn content

Applying geomorphological principles and engineering science to develop a phased sediment management plan for Mount St Helens, Washington

Thirty-seven years post-eruption, erosion of the debris avalanche at Mount St. Helens continues to supply sediment to the Toutle-Cowlitz River system in quantities that have the potential to lower the Level of Protection (LoP) against flooding unacceptably, making this one of the most protracted gravel-bed river disasters to date. The Portland District, US Army Corps of Engineers (USACE) recently revised its long-term plan for sediment management (originally published in 1985), in order to maintain the LoP above the Congressionally-authorised level, while reducing impacts on fish currently listed under the Endangered Species Act, and minimising the overall cost of managing sediment derived from erosion at Mount St Helens. In revising the plan, the USACE drew on evidence gained from sediment monitoring, modelling and uncertainty analysis, coupled with assessment of future LoP trends under a baseline scenario (continuation of the 1985 sediment management strategy) and feasible alternatives. They applied geomorphological principles and used engineering science to develop a Phased Sediment Management Plan that allows for uncertainty concerning future sediment yields by implementing sediment management actions only as, and when, necessary. The phased plan makes best use of the potential to enhance the sediment trap efficiency and storage capacity of the existing Sediment Retention Structure (SRS) by incrementally raising its spillway and using novel hydraulic structures to build islands in the NFTR and steepen the gradient of the sediment plain upstream of the structure. Dredging is held in reserve, to be performed only when necessary to react to unexpectedly high sedimentation events or when the utility of other measures has been expended. The engineering-geomorphic principles and many of the measures in the Phased Sediment Management Plan are transferrable to other gravel-bed river disasters. The overriding message is that monitoring and adaptive management are crucial components of long-term sediment-disaster management, especially in volcanic landscapes where future sediment yields are characterised by uncertainty and natural variability

Statistical Detection of Atypical Aircraft Flights

A computational method and software to implement the method have been developed to sift through vast quantities of digital flight data to alert human analysts to aircraft flights that are statistically atypical in ways that signify that safety may be adversely affected. On a typical day, there are tens of thousands of flights in the United States and several times that number throughout the world. Depending on the specific aircraft design, the volume of data collected by sensors and flight recorders can range from a few dozen to several thousand parameters per second during a flight. Whereas these data have long been utilized in investigating crashes, the present method is oriented toward helping to prevent crashes by enabling routine monitoring of flight operations to identify portions of flights that may be of interest with respect to safety issues

3-D uncertainty-based topographic change detection with structure-from-motion photogrammetry:precision maps for ground control and directly georeferenced surveys

Structure-from-motion (SfM) photogrammetry is revolutionising the collection of detailed topographic data, but insight into geomorphological processes is currently restricted by our limited understanding of SfM survey uncertainties. Here, we present an approach that, for the first time, specifically accounts for the spatially variable precision inherent to photo-based surveys, and enables confidence-bounded quantification of 3-D topographic change. The method uses novel 3-D precision maps that describe the 3-D photogrammetric and georeferencing uncertainty, and determines change through an adapted state-of-the-art fully 3-D point-cloud comparison (M3C2; Lague, et al., 2013), which is particularly valuable for complex topography. We introduce this method by: (1) using simulated UAV surveys, processed in photogrammetric software, to illustrate the spatial variability of precision and the relative influences of photogrammetric (e.g. image network geometry, tie point quality) and georeferencing (e.g. control measurement) considerations; (2) we then present a new Monte Carlo procedure for deriving this information using standard SfM software and integrate it into confidence-bounded change detection; before (3) demonstrating geomorphological application in which we use benchmark TLS data for validation and then estimate sediment budgets through differencing annual SfM surveys of an eroding badland. We show how 3-D precision maps enable more probable erosion patterns to be identified than existing analyses, and how a similar overall survey precision could have been achieved with direct survey georeferencing for camera position data with precision half as good as the GCPs’. Where precision is limited by weak georeferencing (e.g. camera positions with multi-metre precision, such as from a consumer UAV), then overall survey precision can scale as n-½ of the control precision (n = number of images). Our method also provides variance-covariance information for all parameters. Thus, we now open the door for SfM practitioners to use the comprehensive analyses that have underpinned rigorous photogrammetric approaches over the last half-century

Can high resolution 3D topographic surveys provide reliable grain size estimates in gravel bed rivers?

High resolution topographic surveys such as those provided by Structure-from-Motion (SfM) contain a wealth of information that is not always exploited in the generation of Digital Elevation Models (DEMs). In particular, several authors have related sub-metre scale topographic variability (or ‘surface roughness’) to sediment grain size by deriving empirical relationships between the two. In fluvial applications, such relationships permit rapid analysis of the spatial distribution of grain size over entire river reaches, providing improved data to drive three-dimensional hydraulic models, allowing rapid geomorphic monitoring of sub-reach river restoration projects, and enabling more robust characterisation of riverbed habitats. However, comparison of previously published roughness-grain-size relationships shows substantial variability between field sites. Using a combination of over 300 laboratory and field-based SfM surveys, we demonstrate the influence of inherent survey error, irregularity of natural gravels, particle shape, grain packing structure, sorting, and form roughness on roughness-grain-size relationships. Roughness analysis from SfM datasets can accurately predict the diameter of smooth hemispheres, though natural, irregular gravels result in a higher roughness value for a given diameter and different grain shapes yield different relationships. A suite of empirical relationships is presented as a decision tree which improves predictions of grain size. By accounting for differences in patch facies, large improvements in D50 prediction are possible. SfM is capable of providing accurate grain size estimates, although further refinement is needed for poorly sorted gravel patches, for which c-axis percentiles are better predicted than b-axis percentiles