TAMU-CC Repository
The Texas A&M University‐Corpus Christi (TAMU‐CC) repository is an open online site for storing and sharing digital content created or owned by the TAMU‐CC community. Content includes published and unpublished research and scholarship as well as archival materials. The service is managed by the Mary and Jeff Bell Library in cooperation with the Texas Digital Library. Learn more
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Recent Submissions
Stage and discharge prediction from documentary time-lapse imagery
(2024-04-16) Chapman, Kenneth W.; Gilmore, Troy E.; Mehrubeoglu, Mehrube; Chapman, Christian D.; Mittelstet, Aaron R.; Stranzi, John E.
Imagery from fixed, ground-based cameras is rich in qualitative and quantitative information that can improve stream discharge monitoring. For instance, time-lapse imagery may be valuable for filling data gaps when sensors fail and/or during lapses in funding for monitoring programs. In this study, we used a large image archive (>40,000 images from 2012 to 2019) from a fixed, ground-based camera that is part of a documentary watershed imaging project (https://plattebasintimelapse.com/). Scalar image features were extracted from daylight images taken at one-hour intervals. The image features were fused with United States Geological Survey stage and discharge data as response variables from the site. Predictions of stage and discharge for simulated year-long data gaps (2015, 2016, and 2017 water years) were generated from Multi-layer Perceptron, Random Forest Regression, and Support Vector Regression models. A Kalman filter was applied to the predictions to remove noise. Error metrics were calculated, including Nash-Sutcliffe Efficiency (NSE) and an alternative threshold-based performance metric that accounted for seasonal runoff. NSE for the year-long gap predictions ranged from 0.63 to 0.90 for discharge and 0.47 to 0.90 for stage, with greater errors in 2016 when stream discharge during the gap period greatly exceeded discharge during the training periods. Importantly, and in contrast to gap-filling methods that do not use imagery, the high discharge conditions in 2016 could be visually (qualitatively) verified from the image data. Half-year test sets were created for 2016 to include higher discharges in the training sets, thus improving model performance. While additional machine learning algorithms and tuning parameters for selected models should be tested further, this study demonstrates the potential value of ground-based time-lapse images for filling large gaps in hydrologic time series data. Cameras dedicated for hydrologic sensing, including nighttime imagery, could further improve results.
Mathematics education researchers’ practices in interdisciplinary collaborations: Embracing different ways of knowing
(2024-03-21) Suazo-Flores, Elizabeth; Walker III, William S.; Kastberg, Signe E.; Aqazade, Mahtob; Alyami, Hanan
Mathematics education researchers (MERs) use practices unique to the mathematics education discipline to conduct their work. MERs’ practices, i.e., ways of being, interacting, and operating, define the field of mathematics education, are initially learned in doctoral preparation programs, and are encouraged and sanctioned by conferences and publications. Disciplinary practices facilitate MERs’ interactions within mathematics education. When working in interdisciplinary groups, differences in disciplinary ways of being, interacting, and operating can create challenges with completing research and other work. Since MERs’ engagement in interdisciplinary collaborations is encouraged and can result in products contributing to the evolution of the mathematics education discipline, it is important to explore what practices MERs use in interdisciplinary collaborations. We interviewed four MERs who led international interdisciplinary collaborations and used qualitative content analysis to create descriptions of practices described by MERs in their collaborations. Five practices were common between the MERs in interdisciplinary collaborations. MERs conducted interdisciplinary work by using practices that allowed them to situate themselves and others in the group (i.e., being practices), develop ideas (i.e., interacting practices), work towards common goals, and use structures to get the work done (i.e., operating practices). We argue that MERs developed new practices to position themselves and others, interact with practitioners from other disciplines, and get interdisciplinary work done. This study contributes to the evolution of the mathematics education discipline by offering five practices that can orient MERs to conducting interdisciplinary work and discussing how MERs experience interdisciplinary collaborations beyond providing mathematics education expertise.
Simplified indoor localization using Bluetooth beacons and received signal strength fingerprinting with smartwatch
(2024-03-25) Bouse, Leana; King, Scott A.; Chu, Tianxing
Variations in Global Positioning Systems (GPSs) have been used for tracking users’ locations.
However, when location tracking is needed for an indoor space, such as a house or building, then an alternative means of precise position tracking may be required because GPS signals can be severely attenuated or completely blocked. In our approach to indoor positioning, we developed an indoor localization system that minimizes the amount of effort and cost needed by the end user to put the system to use. This indoor localization system detects the user’s room-level location within a house or indoor space in which the system has been installed. We combine the use of Bluetooth Low Energy beacons and a smartwatch Bluetooth scanner to determine which room the user is located in. Our system has been developed specifically to create a low-complexity localization system using the Nearest Neighbor algorithm and a moving average filter to improve results. We evaluated our system across a household under two different operating conditions: first, using three rooms in the house, and then using five rooms. The system was able to achieve an overall accuracy of 85.9% when testing in three rooms and 92.106% across five rooms. Accuracy also varied by region, with most of the regions performing above 96% accuracy, and most false-positive incidents occurring within transitory areas between regions. By reducing the amount of processing used by our approach, the end-user is able to use other applications and services on the smartwatch concurrently.
Analysing micro- and nanoplastics with cutting-edge infrared spectroscopy techniques: A critical review
(2024-03-27) Xie, Junhao; Gowen, Aoife; Xu, Wei; Xu, Junli
The escalating prominence of micro- and nanoplastics (MNPs) as emerging anthropogenic pollutants has sparked widespread scientific and public interest. These minuscule particles pervade the global environment, permeating drinking water and food sources, prompting concerns regarding their environmental impacts and potential risks to human health. In recent years, the field of MNP research has witnessed the development and application of cutting-edge infrared (IR) spectroscopic instruments. This review focuses on the recent application of advanced IR spectroscopic techniques and relevant instrumentation to analyse MNPs. A comprehensive literature search was conducted, encompassing articles published within the past three years. The findings revealed that Fourier transform infrared (FTIR) spectroscopy stands as the most used technique, with focal plane array FTIR (FPA-FTIR) representing the cutting edge in FTIR spectroscopy. The second most popular technique is quantum cascade laser infrared (QCL-IR) spectroscopy, which has facilitated rapid analysis of plastic particles. Following closely is optical photothermal infrared (O-PTIR) spectroscopy, which can furnish submicron spatial resolution. Subsequently, there is atomic force microscopy-based infrared (AFM-IR) spectroscopy, which has made it feasible to analyse MNPs at the nanoscale level. The most advanced IR instruments identified in articles covered in this review were compared. Comparison metrics encompass substrates/filters, data quality, spatial resolution, data acquisition speed, data processing and cost. The limitations of these IR instruments were identified, and recommendations to address these limitations were proposed. The findings of this review offer valuable guidance to MNP researchers in selecting suitable instrumentation for their research experiments, thereby facilitating advancements in research aimed at enhancing our understanding of the environmental and human health risks associated with MNPs.
Insights into glacial processes from micromorphology of silt-sized sediment
(2023-06-20) Lepp, Allison P.; Miller, Lauren E.; Anderson, John B.; O'Regan, Matt; Winsborrow, Monica C.M.; Smith, James A.; Hillenbrand, Claus-Dieter; Wellner, Julia S.; Prothro, Lindsay O.; Podolskiy, Evgeny A.
Meltwater plume deposits (MPDs) from marine sediment cores have elucidated clearly connected, yet difficult to constrain, relationships between ice-marginal landform construction, grounding-zone retreat patterns, and subglacial hydrology for several glacial systems in both hemispheres. Few attempts have been made, however, to infer coveted details of subglacial hydrology, such as flow regime, drainage style, and mode(s) of sediment transport through time from grain-scale characteristics of MPDs. Using MPD, till, and ice-proximal diamicton samples collected offshore of six modern and relict glacial systems in both hemispheres, we examine whether grain-shape distributions and microtexture assemblages (collectively, grain micromorphology) of the silt fraction are the result of subglacial meltwater action, or are indistinguishable from glacial proximal and subglacial sediments from the same region. We find that of all grains imaged (n=9,400), three-quarters can be described by one-quarter of the full range of measured shape morphometrics, indicating widespread and efficient abrasive processes in subglacial environments. Microtexture analysis reveals that while grains comprising MPDs show evidence of edge rounding more often than tills, fluvial microtextures occur in modest amounts on grain surfaces. Furthermore, MPDs retain many mechanical (i.e., glacial) textures in comparable abundances to tills. Significant alteration of MPDs from till sources is observed for systems (1) for which intensive, potentially catastrophic, meltwater drainage events in the Holocene are inferred from marine geologic records, and (2) with comparatively less mature till grains and a contribution of supraglacial melt to the bed, indicating that quantifiable grain-shape alteration of MPDs may reflect a combination of young till, high-energy flow of subglacial meltwater, persistent sediment entrainment, and/or long sediment transport distances. We encourage future works to integrate grain micromorphology into site-specific marine sediment analyses, which may distinguish periods of persistent, well-connected subglacial discharge from periods of sporadic or disorganized drainage and provide context needed to estimate sediment fluxes and characterize ice response to subglacial meltwater transmission. In addition, this work demonstrates that glacial and fluvial surface textures are retained on silts in adequate abundance for microtexture analysis.