Scholarly Work - Civil Engineering

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    Characterizing sub-glacial hydrology using radar simulations
    (Copernicus GmbH, 2024-04) Pierce, Chris; Gerekos, Christopher; Skidmore, Mark; Beem, Lucas; Blankenship, Don; Sang Lee, Won; Adams, Ed; Lee, Choon-Ki; Stutz, Jamey
    The structure and distribution of sub-glacial water directly influences Antarctic ice mass loss by reducing or enhancing basal shear stress and accelerating grounding line retreat. A common technique for detecting sub-glacial water involves analyzing the spatial variation in reflectivity from an airborne radar echo sounding (RES) survey. Basic RES analysis exploits the high dielectric contrast between water and most other substrate materials, where a reflectivity increase ≥ 15 dB is frequently correlated with the presence of sub-glacial water. There are surprisingly few additional tools to further characterize the size, shape, or extent of hydrological systems beneath large ice masses. We adapted an existing radar backscattering simulator to model RES reflections from sub-glacial water structures using the University of Texas Institute for Geophysics (UTIG) Multifrequency Airborne Radar Sounder with Full-phase Assessment (MARFA) instrument. Our series of hypothetical simulation cases modeled water structures from 5 to 50 m wide, surrounded by bed materials of varying roughness. We compared the relative reflectivity from rounded Röthlisberger channels and specular flat canals, showing both types of channels exhibit a positive correlation between size and reflectivity. Large (> 20 m), flat canals can increase reflectivity by more than 20 dB, while equivalent Röthlisberger channels show only modest reflectivity gains of 8–13 dB. Changes in substrate roughness may also alter observed reflectivity by 3–6 dB. All of these results indicate that a sophisticated approach to RES interpretation can be useful in constraining the size and shape of sub-glacial water features. However, a highly nuanced treatment of the geometric context is necessary. Finally, we compared simulated outputs to actual reflectivity from a single RES flight line collected over Thwaites Glacier in 2022. The flight line crosses a previously proposed Röthlisberger channel route, with an obvious bright bed reflection in the radargram. Through multiple simulations comparing various water system geometries, such as canals and sub-glacial lakes, we demonstrated the important role that topography and water geometry can play in observed RES reflectivity. From the scenarios that we tested, we concluded the bright reflector from our RES flight line cannot be a Röthlisberger channel but could be consistent with a series of flat canals or a sub-glacial lake. However, we note our simulations were not exhaustive of all possible sub-glacial water configurations. The approach outlined here has broad applicability for studying the basal environment of large glaciers. We expect to apply this technique when constraining the geometry and extent of many sub-glacial hydrologic structures in the future. Further research may also include comprehensive investigations of the impact of sub-glacial roughness, substrate heterogeneity, and computational efficiencies enabling more complex and complete simulations.
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    Mapping surface hoar from near-infrared texture in a laboratory
    (Copernicus GmbH, 2024-05) Dillon, James; Donahue, Christopher; Schehrer, Evan; Birkeland, Karl; Hammonds, Kevin
    Surface hoar crystals are snow grains that form when water vapor deposits on the snow surface. Once buried, surface hoar creates a weak layer in the snowpack that can later cause large avalanches to occur. The formation and persistence of surface hoar are highly spatiotemporally variable, making its detection difficult. Remote-sensing technology capable of detecting the presence and spatial distribution of surface hoar would be beneficial for avalanche forecasting, but this capability has yet to be developed. Here, we hypothesize that near-infrared (NIR) texture, defined as the spatial variability of reflectance magnitude, may produce an optical signature unique to surface hoar due to the distinct shape and orientation of the grains. We tested this hypothesis by performing reflectance experiments in a controlled cold laboratory environment to evaluate the potential and accuracy of surface hoar mapping from NIR texture using a near-infrared hyperspectral imager (NIR-HSI) and a lidar operating at 1064 nm. We analyzed 41 snow samples, three of which were surface hoar and 38 of which consisted of other grain morphologies. When using NIR-HSI under direct and diffuse illumination, we found that surface hoar displayed higher NIR texture relative to all other grain shapes across numerous spectral bands and a wide range of spatial resolutions (0.5–50 mm). Due to the large number of spectral- and spatial-resolution combinations, we conducted a detailed samplewise case study at 1324 nm spectral and 10 mm spatial resolution. The case study resulted in the median texture of surface hoar being 1.3 to 8.6 times greater than that of the 38 other samples under direct and diffuse illumination (p < 0.05 in all cases). Using lidar, surface hoar also exhibited significantly increased NIR texture in 30 out of 38 samples, but only at select (5–25 mm) spatial resolutions. Leveraging these results, we propose a simple binary classification algorithm to map the extent of surface hoar on a pixelwise basis using both the NIR-HSI and lidar instruments. The NIR-HSI under direct and diffuse illumination performed best, with a median accuracy of 96.91 % and 97.37 %, respectively. Conversely, the median classification accuracy achieved with lidar was only 66.99 %. Further, to assess the repeatability of our method and demonstrate its mapping capacity, we ran the algorithm on a new sample with mixed microstructures, with an accuracy of 99.61 % and 96.15 % achieved using NIR-HSI under direct and diffuse illumination, respectively. As NIR-HSI detectors become increasingly available, our findings demonstrate the potential of a new tool for avalanche forecasters to remotely assess the spatiotemporal variability of surface hoar, which would improve avalanche forecasts and potentially save lives.
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    Two-Lane Highways: Indispensable Rural Mobility
    (MDPI AG, 2022-03) Al-Kaisy, Ahmed
    Two-lane highways refer to roadways consisting of two lanes in the cross section, one for each direction of travel. Occasionally, passing lanes may be added to one or two sides of the roadway extending the cross section to three or four lanes at those locations. In this entry, two-lane highways strictly refer to roads in rural areas meeting the previous definition and do not include urban and suburban streets.
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    Capacity at All-Way Stop Control Intersections: Case Study
    (SAGE Publications, 2023-08) Al-Kaisy, Ahmed; Doruk, Dorukhan
    This paper presents an empirical investigation into the capacity of all-way stop-controlled (AWSC) intersections. Video data was collected over four days at an AWSC intersection site in Bozeman, Montana. The site is characterized by single-lane approaches and high level of vehicular and pedestrian traffic. Using strict protocols, video records were processed at the individual vehicle level and several information metrics were extracted for each vehicle in the data set on all approaches. Study results indicate that the total intersection capacity at the study site varied between 400 and 1,400 vehicles per hour. The study suggests that the wide range of capacity observations is largely associated with the pedestrian crossing activity at the study site. Statistical tests confirmed that both pedestrian crossing activity and the level of conflict have significant effects on intersection capacity at the 95% confidence level. For movement type, the right-turn movement was not found to have a significant effect on intersection capacity while left-turn movement was found to negatively affect the intersection capacity. The results presented in this paper offer valuable information on AWSC intersection capacity, given the limited amount of information in the literature and the dated nature of those empirical observations.
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    A Novel Network Screening Methodology for Rural Low-Volume Roads
    (Scientific Research Publishing, Inc., 2023-01) Al-Kaisy, Ahmed; Raza, Sajid
    Low-volume roads (LVRs) are an integral part of the rural transportation network providing access to remote rural areas and facilitating the movement of goods from farms to markets. These roads pose unique challenges for highway agencies including those related to safety management on the highway network. Specifically, traditional network screening methods using crash history can be effective in screening rural highways with higher traffic volumes and more frequent crashes. However, these traditional methods are often ineffective in screening LVR networks due to low traffic volumes and the sporadic nature of crash occurrence. Further, many of the LVRs are owned and operated by local agencies that may lack access to detailed crash, traffic and roadway data and the technical expertise within their staff. Therefore, there is a need for more efficient and practical network screening approaches to facilitate safety management programs on these roads. This study proposes one such approach which utilizes a heuristic scoring scheme in assessing the level of risk/safety for the purpose of network screening. The proposed scheme is developed based on the principles of US Highway Safety Manual (HSM) analysis procedures for rural highways and the fundamentals in safety science. The primary application of the proposed scheme is for ranking sites in network screening applications or for comparing multiple improvement alternatives at a specific site. The proposed approach does not require access to detailed databases, technical expertise, or exact information, making it an invaluable tool for small agencies and local governments (e.g. counties, townships, tribal governments, etc.).
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    A New Approach for Identifying Safety Improvement Sites on Rural Highways: A Validation Study
    (MDPI AG, 2024-02) Dhakal, Bishal; Al-Kaisy, Ahmed
    The research presented in this paper examines a new proposed approach for identifying safety improvement sites on rural highways. Unlike conventional approaches, the proposed approach does not require crash history, but rather utilizes classified variables for traffic volume, geometric features, and roadside characteristics that do not require access to exact data or extensive technical expertise. The research validates the performance of the proposed approach using field data from a large sample of rural two-lane highway segments in the state of Oregon including traffic, roadway, and crash data. A mathematical model for the prediction of the EB expected number of crashes using multivariate regression analysis is developed and used as the network screening criterion. The model’s independent variables include roadway geometry, roadside characteristics, and traffic exposure, while the dependent variable is the EB expected number of crashes. Using observed crash history as a reference, the performance of the proposed approach was compared to two of the well-established methods in practice, namely, the Empirical Bayes (EB) and the potential for safety improvement (PSI) methods. The study results suggest that by using crash density for highway segments, the performance of the proposed method was lower than that of the EB and PSI methods. This is despite the high R-square value of the predictive model used in the proposed method. However, when using crash frequencies for highway segments, the performance of the proposed method was found comparable to the well-established EB and PSI methods.
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    Pharmaceutical impacts on aerobic granular sludge morphology and potential implications for abiotic removal
    (Elsevier, 2024-02) Bodle, Kylie B.; Kirkland, Catherine M.
    The goal of this study was to investigate abiotic pharmaceutical removal and abiotic pharmaceutical effects on aerobic granular sludge morphology. For 80 days, a pharmaceutical mixture containing approximately 150 μg/L each of diclofenac, erythromycin, and gemfibrozil was fed to an aerobic granular sludge sequencing batch reactor and granule characteristics were compared with those from a control reactor. Aqueous and solid phase pharmaceutical concentrations were monitored and staining was used to assess changes in biofilm structures. Solid phase pharmaceutical concentrations were elevated over the first 12 days of dosing; however, they then dropped, indicative of desorption. The lipid content in pharmaceutical-exposed granules declined by approximately half over the dosing period, though the relative concentrations of other key biofilm components (proteins, alpha-, and beta-polysaccharides) did not change. Batch experiments were conducted to try to find an explanation for the desorption observed, but reduced solid phase pharmaceutical concentrations could not be linked with the presence of common wastewater constituents such as ammonia or phosphate. Sorption of all three compounds was modeled best by the Henry isotherm, indicating that, even at 150 μg/L, granules’ sorption site coverage was incomplete. Altogether, this study demonstrates that simplified batch systems may not accurately represent the complex abiotic processes occurring in flow-through, biotic systems.
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    Treatment performance and microbial community structure in an aerobic granular sludge sequencing batch reactor amended with diclofenac, erythromycin, and gemfibrozil
    (Frontiers Media SA, 2023-09) Bodle, Kylie B.; Mueller, Rebecca C.; Pernat, Madeline R.; Kirkland, Catherine M.
    This study characterizes the effects of three commonly detected pharmaceuticals—diclofenac, erythromycin, and gemfibrozil—on aerobic granular sludge. Approximately 150 µg/L of each pharmaceutical was fed in the influent to a sequencing batch reactor for 80 days, and the performance of the test reactor was compared with that of a control reactor. Wastewater treatment efficacy in the test reactor dropped by approximately 30-40%, and ammonia oxidation was particularly inhibited. The relative abundance of active Rhodocyclaceae, Nitrosomonadaceae, and Nitrospiraceae families declined throughout exposure, likely explaining reductions in wastewater treatment performance. Pharmaceuticals were temporarily removed in the first 12 days of the test via both sorption and degradation; both removal processes declined sharply thereafter. This study demonstrates that aerobic granular sludge may successfully remove pharmaceuticals in the short term, but long-term tests are necessary to confirm if pharmaceutical removal is sustainable.
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    Flow-Control Plates to Manage Denil Fishways in Irrigation Diversions for Upstream Passage of Arctic Grayling
    (U.S. Fish and Wildlife Service, 2023-06) Plymesser, Kathryn; Blue, Tyler; Kappenman, Kevin M.; Blank, Matthew; Cahoon, Joel; Dockery, David
    Small-stream irrigation diversions are key elements of many on-farm irrigation systems but can act as barriers to aquatic species. Denil fishways have been installed at irrigation diversion structures throughout the Big Hole River watershed in Montana to provide upstream passage for a population of Arctic Grayling Thymallus arcticus. When stream flows are low and irrigation demand is high, irrigators look for ways to maintain adequate diversion, but doing so may reduce the effectiveness of the fishways. In response, agencies and irrigators have proposed flow-control plates placed at the upstream end of fishways. We conducted laboratory-based fishway efficiency experiments with Arctic Grayling placed in an open-channel flume fitted with a Denil fishway and three flow plates. Of the total 200 fish that we used, the fishway entrance attracted 154 fish and we counted these fish as participants. We operated the fishway under varying flow conditions using three flow-control plate treatments and a control to investigate 1) the extent to which each treatment reduced flow compared to the control, and 2) the extent to which each treatment impacted passage success of Arctic Grayling relative to the control. We measured passage success as the ratio of the number of fish that fully ascended the fishway treatment to the number of participant fish attracted to the fishway treatment. One of the three plates, the Denil slot treatment, showed no evidence of reducing either flow or passage success. Another plate, the standard treatment, showed no evidence of reducing flow but moderate evidence of reducing passage success (P = 0.03). The only treatment to significantly reduce water flow rate was the narrowed Denil slot treatment and there was no evidence this treatment reduced passage in comparison to the control. Over all trials, water flow rate through the Denil fishway had a strong positive influence on fish passage success.
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    Impact of deicing salts on pervious concrete pavement
    (Frontiers Media SA, 2023-06) Feng, Lichao; Zhang, Yongran; Wang, Xiaowei; Mery, Stephene; Akin, Michelle; Li, Mengchao; Xie, Ning; Li, Zhenming; Shi, Xianming
    Two pervious concrete projects (named as SR28 and SR431), with the same mixture design but different winter maintenance activities, were included in this research. Both projects are located in the Lake Tahoe area, Nevada, United States. Testing results indicated that the mechanical properties were significantly higher in SR28 cored samples than the ones in SR431. It was found that the SR28 pieces have fewer air voids, while the SR431 samples have higher water absorption and hydraulic conductivity, and the SR28 samples show fare better performance against repeated freezing and thawing cycles than the SR431 ones. scanning electron microscope pictures of crack surfaces in cores taken from SR28 indicate that the cement binder phase has been largely retained. However, in the coring sample of SR431, needle-shaped residues can be seen within the cement binder phase and an abundance of precipitated micro-sized crystalized particles can be observed. On a micrometer scale, the μCT examination reveals that the porosity of SR28 samples is significantly less than that of SR431. The analyzing results give a clue to demonstrate the durability of pervious concrete pavement can be attributed to the construction quality control, maintenance activity, or the weather and locations of the field sites.
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    High-Level Assessment ofStatewide GNSS-RTN Business Models
    (2023-06) Al-Kaisy, Ahmed; Raza, Sajid
    The applications of geospatial technologies and positioning data embrace every sphere of modern-day science and industry where geographical positioning matters. Among all other fields, geospatial technology plays a remarkable role in the transportation sector and has the potential to play an even more critical role in future autonomous transportation systems. In this regard, the GNSS-Real-Time Network (GNSS-RTN) technology is promising in meeting the needs of automation in most advanced transportation applications. The GNSS-RTN is a satellite-based positioning system that uses a network of reference stations to provide centimeter-level accuracy in positioning data in real-time. The technical aspect and working technology of GNSS-RTN are widely studied, however, only limited research has been conducted on the various GNSS-RTN business models currently in use nationally and internationally. Therefore, this study aims at assessing the various GNSS-RTN business models currently used in practice as well as those that are deemed potentially viable but have not yet moved to practice. Eight different business models were cataloged and used in the current assessment. All business models were assessed using three criteria: state control, sustainability, and state/agency costs. The findings of this research are important in helping state agencies make informed decisions as they build, expand or manage their own GNSS-RTN systems.
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    Pharmaceutical Sorption to Lab Materials May Overestimate Rates of Removal in Lab-Scale Bioreactors
    (Springer Science and Business Media LLC, 2022-11) Bodle, Kylie B.; Pernat, Madeline R.; Kirkland, Catherine M.
    Environmental contamination from pharmaceuticals has received increased attention from researchers in the past 20 years. As such, numerous lab-scale studies have sought to characterize the effects of these contaminants on various targets, as well as determine improved removal methods. Many studies have used lab-scale bioreactors to investigate pharmaceutical effects on wastewater bacteria, as wastewater treatment plants often act as reservoirs for pharmaceuticals. However, few—if any—of these studies report the specific lab materials used during testing, such as tubing or pipette tip type. In this study, the pharmaceuticals erythromycin, diclofenac, and gemfibrozil were exposed to different micropipette tips, syringe filters, and tubing types, and losses over time were evaluated. Losses to tubing and syringe filters were particularly significant and neared 100%, depending on the pharmaceutical compound and length of exposure time. Results discussed herein indicate that pharmaceutical sorption to various lab supplies results in decreases to both dosed and quantified pharmaceutical concentrations. Studies that fail to consider this source of loss may therefore draw inaccurate conclusions about pharmaceutical effects or removal efficiencies.
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    Mapping liquid water content in snow at the millimeter scale: an intercomparison of mixed-phase optical property models using hyperspectral imaging and in situ measurements
    (Copernicus Publications, 2022-01) Donahue, Christopher; Skiles, S. McKenzie; Hammonds, Kevin
    It is well understood that the distribution and quantity of liquid water in snow is relevant for snow hydrology and avalanche forecasting, yet detecting and quantifying liquid water in snow remains a challenge from the micro- to the macro-scale. Using near-infrared (NIR) spectral reflectance measurements, previous case studies have demonstrated the capability to retrieve surface liquid water content (LWC) of wet snow by leveraging shifts in the complex refractive index between ice and water. However, different models to represent mixed-phase optical properties have been proposed, including (1) internally mixed ice and water spheres, (2) internally mixed water-coated ice spheres, and (3) externally mixed interstitial ice and water spheres. Here, from within a controlled laboratory environment, we determined the optimal mixed-phase optical property model for simulating wet snow reflectance using a combination of NIR hyperspectral imaging, radiative transfer simulations (Discrete Ordinate Radiative Transfer model, DISORT), and an independent dielectric LWC measurement (SLF Snow Sensor). Maps of LWC were produced by finding the lowest residual between measured reflectance and simulated reflectance in spectral libraries, generated for each model with varying LWC and grain size, and assessed against the in situ LWC sensor. Our results show that the externally mixed model performed the best, retrieving LWC with an uncertainty of ∼1 %, while the simultaneously retrieved grain size better represented wet snow relative to the established scaled band area method. Furthermore, the LWC retrieval method was demonstrated in the field by imaging a snowpit sidewall during melt conditions and mapping LWC distribution in unprecedented detail, allowing for visualization of pooling water and flow features.
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    Test of 90-Foot Post-Tensioned Concrete Girder with Unbonded Tendons
    (American Concrete Institute, 2021-09) Pujol, Santiago; Fick, Damon; Fargier-Gabaldón, Luis B.
    A full-scale post-tensioned concrete girder with unbonded tendons was tested to investigate whether, under vertical forces, a full flexural mechanism (with three hinging regions) would form, and what strand stress would be reached in that condition. The specimen was a 0.91 m (3 ft) deep T-beam with a 2.43 m (8 ft) wide flange, spanning over two supports spaced at 18.3 m (60 ft) with two 4.6 m (15 ft) cantilevers and featured a parabolic tendon profile. Transverse reinforcement to resist shear and longitudinal “mild” reinforcement were also provided. A uniformly distributed load was applied on the main span and concentrated loads were applied to the ends of the cantilevers. While the main span was loaded, the two concentrated loads on the cantilevers provided a reaction force to minimize rotations at supports. At the end of the test, the girder deflected 278 mm (10.9 in., L/65) and carried 231 kN/m (15.5 kip/ft) over the main span. A full plastic mechanism formed with hinging regions at supports and at midspan. Test results suggest the unbonded tendons nearly reached their nominal strength (fpu) and that a limit analysis is adequate for estimating the flexural strength of comparable post-tensioned girders.
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    International Journal of Multiphase Flow
    (Elsevier BV, 2021-07) Tagliavini, Giorgia; McCorquodale, Mark; Westbrook, Chris; Corso, Pascal; Krol, Quirine; Holzner, Markus
    This study considers complex ice particles falling in the atmosphere: predicting the drag of such particles is important for developing of climate models parameterizations. A Delayed-Detached Eddy Simulation model is developed to predict the drag coefficient of snowflakes falling at Reynolds number between 50 and 2200. We first consider the case where the orientation of the particle is known a posteriori, and evaluate our results against laboratory experiments using 3D-printed particles of the same shape, falling at the same Reynolds number. Close agreement is found in cases where the particles fall stably, while a more complex behavior is observed in cases where the flow is unsteady. The second objective of this study is to evaluate methods for estimating the drag coefficient when the orientation of the particles is not known a posteriori. We find that a suitable average of two orientations corresponding to the minimum and maximum eigenvalues of the inertia tensor provides a good estimate of the particle drag coefficient. Meanwhile, existing correlations for the drag on non-spherical particles produce large errors (≈50%). A new formula to estimate snow particles settling velocity is also proposed. Our approach provides a framework to investigate the aerodynamics of complex snowflakes and is relevant to other problems that involve the sedimentation of irregular particles in viscous fluids.
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    Empirical Bayes application on low-volume roads: Oregon case study
    (Elsevier BV, 2021-12) Al-Kaisy, Ahmed; Huda, Kazi Tahsin
    ntroduction: This paper investigates the Empirical Bayes (EB) method and the Highway Safety Manual (HSM) predictive methodology for network screening on low-volume roads in Oregon. Method: A study sample of around 870 miles of rural two-lane roadways with extensive crash, traffic and roadway information was used in this investigation. To understand the effect of low traffic exposure in estimating the EB expected number of crashes, the contributions of both the observed and the HSM predicted number of crashes were analyzed. Results and Conclusions: The study found that, on low-volume roads, the predicted number of crashes is the major contributor in estimating the EB expected number of crashes. The study also found a large discrepancy between the observed and the predicted number of crashes using the HSM procedures calibrated for the state of Oregon, which could partly be attributed to the unique attributes of low-volume roads that are different from the rest of the network. However, the expected number of crashes for the study sample using the HSM EB method was reasonably close to the observed number of crashes over the 10-year study period. Practical Applications: Based on the findings, it can still be very effective to use network screening methods that rely primarily on risk factors for low-volume road networks. This is especially applicable in situations where accurate and reliable crash data are not available.
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    Reanalysis of Polythermal Glacier Thermal Structure Using Radar Diffraction Focusing
    (American Geophysical Union, 2022-01) Delf, Richard; Bingham, Robert G.; Curtis, Andrew; Singh, Satyan; Giannopoulos, Antonios; Schwarz, Benjamin; Borstad, Chris P.
    Ground-penetrating radar (GPR) is widely used on polythermal glaciers to image bed topography and detect internal scatter due to water inclusions in temperate ice. The glaciological importance of this is twofold: bed topography is a primary component for modeling the long-term evolution of glaciers and ice sheets, and the presence of temperate ice and associated englacial water significantly reduces overall ice viscosity. Englacial water has a direct influence on radar velocity, which can result in incorrect observations of bed topography due to errors in depth conversion. Assessment of radar velocities often requires multi-offset surveys, yet these are logistically challenging and time consuming to acquire, hence techniques to extract velocity from common-offset data are required. We calculate englacial radar velocity from common offset GPR data collected on Von Postbreen, a polythermal glacier in Svalbard. We first separate and enhance the diffracted wavefield by systematically assessing data coherence. We then use the focusing metric of negative entropy to deduce a migration velocity field and produce a velocity model which varies spatially across the glacier. We show that this velocity field successfully differentiates between areas of cold and temperate ice and can detect lateral variations in radar velocity close to the glacier bed. This velocity field results in consistently lower ice depths relative to those derived from a commonly assumed constant velocity, with an average difference of 4.9 ± 2.5% of local ice depth. This indicates that diffraction focusing and velocity estimation are crucial in retrieving correct bed topography in the presence of temperate ice.
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    The Use of Fiber-Reinforced Polymers in Wildlife Crossing Infrastructure
    (MDPI, 2020-02) Bell, Matthew; Fick, Damon; Ament, Rob; Lister, Nina-Marie
    The proven effectiveness of highway crossing infrastructure to mitigate wildlife-vehicle collisions with large animals has made it a preferred method for increasing motorist and animal safety along road networks around the world. The crossing structures also provide safe passage for small- and medium-sized wildlife. Current methods to build these structures use concrete and steel, which often result in high costs due to the long duration of construction and the heavy machinery required to assemble the materials. Recently, engineers and architects are finding new applications of fiber-reinforced polymer (FRP) composites, due to their high strength-to-weight ratio and low life-cycle costs. This material is better suited to withstand environmental elements and the static and dynamic loads required of wildlife infrastructure. Although carbon and glass fibers along with new synthetic resins are most commonly used, current research suggests an increasing incorporation and use of bio-based and recycled materials. Since FRP bridges are corrosion resistant and hold their structural properties over time, owners of the bridge can benefit by reducing costly and time-consuming maintenance over its lifetime. Adapting FRP bridges for use as wildlife crossing structures can contribute to the long-term goals of improving motorist and passenger safety, conserving wildlife and increasing cost efficiency, while at the same time reducing plastics in landfills.
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    Swimming Performance of Rainbow Trout and Westslope Cutthroat Trout in an Open-Channel Flume
    (2020-06) Blank, Matt D.; Kappenman, Kevin M.; Plymesser, Kathryn; Banner, Katharine M.; Cahoon, Joel
    We used an open-channel flume to characterize the swimming performance of Rainbow Trout Oncorhynchus mykiss and Westslope Cutthroat Trout Oncorhynchus clarki lewisi ranging nominally in fork length from 15 to 30 cm. With an open-channel flume, we observed volitional swim performance of wild-caught Rainbow Trout and Westslope Cutthroat Trout; the fish were not coerced, prodded, or spooked into action. We also observed the maximum short-duration swim speed of the fish, providing important effective leap or velocity challenge information for the design of intentional barriers. We conducted the experiment with a consistently low water velocity challenge and characterized swim speeds by using weighted least-squares regression, revealing no evidence of a difference in swim speeds between the two species. We estimated the overall average swim speed for Rainbow Trout to be 0.84 m/s (SE = 0.02), with a 95% confidence interval of 0.79–0.89 m/s, and that for Westslope Cutthroat Trout to be 0.84 m/s (SE = 0.03), with a 95% confidence interval of 0.78–0.90 m/s. The maximum swim speeds observed were 2.72 m/s for Rainbow Trout and 3.55 m/s for Westslope Cutthroat Trout. The project results provide new information on the swimming ability of wild Rainbow Trout and Westslope Cutthroat Trout that can be used to improve fish passage or barrier design.
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    Biomineralization of Plastic Waste to Improve the Strength of Plastic-Reinforced Cement Mortar
    (2021-04) Kane, Seth; Thane, Abby; Espinal, Michael; Lunday, Kendra; Armagan, Hakan; Phillips, Adrienne J.; Heveran, Chelsea M.; Ryan, Cecily A.
    The development of methods to reuse large volumes of plastic waste is essential to curb the environmental impact of plastic pollution. Plastic-reinforced cementitious materials (PRCs), such as plastic-reinforced mortar (PRM), may be potential avenues to productively use large quantities of low-value plastic waste. However, poor bonding between the plastic and cement matrix reduces the strength of PRCs, limiting its viable applications. In this study, calcium carbonate biomineralization techniques were applied to coat plastic waste and improved the compressive strength of PRM. Two biomineralization treatments were examined: enzymatically induced calcium carbonate precipitation (EICP) and microbially induced calcium carbonate precipitation (MICP). MICP treatment of polyethylene terephthalate (PET) resulted in PRMs with compressive strengths similar to that of plastic-free mortar and higher than the compressive strengths of PRMs with untreated or EICP-treated PET. Based on the results of this study, MICP was used to treat hard-to-recycle types 3–7 plastic waste. No plastics investigated in this study inhibited the MICP process. PRM samples with 5% MICP-treated polyvinyl chloride (PVC) and mixed type 3–7 plastic had compressive strengths similar to plastic-free mortar. These results indicate that MICP treatment can improve PRM strength and that MICP-treated PRM shows promise as a method to reuse plastic waste.
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