93887 research outputs found
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Feature Extraction of Steel Corrosion based on XCT Scanning and Deep Learning Model
No full textAccurate quantification and analysis of steel corrosion is crucial for reliability assessment studies of in-service reinforced concrete structures. However, the pixel-level cross-sectional data provided by X-ray computed tomography (XCT) proves difficult to quantify, especially for the amorphous corrosion products filled in mortar, due to the absence of robust feature extraction methods. In this study, multiple deep learning models were trained to automatically identify corrosion products from a large number of XCT images. The database comprised XCT images obtained from a RC component subjected to chloride-rich environment for four years. The results indicate that deep learning models can segment different regions of XCT images with high accuracy. Among the models, the K-Net model performed the best on this dataset, achieving an accuracy of 94.60%, and a mean Precision (mPrecision) of 88.21%. This advance makes it possible to automatically extract parameters that characterise steel corrosion and to assess the damage to RC structures caused by corrosion
Mortal Writing: Toward Braver Concepts of “Better Writers,” Peerness, and Nationality
No full textReflecting on experiences with two Afghan students writing in response to events following the U.S. withdrawal from Afghanistan in 2021, this essay challenges traditional writing center practices in response to the evolving and urgent writing needs of diverse (international) student populations. Focusing on the intersectional identities of student writers and the geopolitical realities they face, we develop further the call to transform writing centers into “brave spaces.” Deploying this framework of bravery, we call for a reevaluation of the concept of “better writers,” of empathy constructed primarily through peerness, and of the current conceptualization of nationality in writing center scholarship. Writing centers as a discipline must reconceptualize these constructs of our theory and practice if they are to become brave(r) spaces that support students as they fight for social justice and survival
A simple approach to delineating field boundaries using satellite imagery
No full textAccurate delineation of agricultural field boundaries is crucial for farm management, research, and policy development. However, publicly available boundary datasets are often limited in accuracy, very expensive, or use deep learning architectures that require extensive annotated data that are not available, limiting access. This project presents a simple, image-processing-based method for delineating field boundaries using openly available satellite images. Our method manipulates the images using a variety of image processing techniques and is able to generate an accurate boundary for a selected field. By providing a simple and accessible solution, this approach has the potential to transform boundary delineation practices, increasing the efficiency of farmers, advisors, and researchers. Our method’s simplicity and accuracy highlight a path from innovation to a real-world impact
An AI-enhanced Soft Robotic System for Selective Strawberry Harvesting
No full textStrawberry harvesting is labor-intensive and requires delicate, selective handling. Current robotic solutions rely mostly on rigid arms, which lack flexibility and often cause fruit damage or require complex mechanisms. To address this, we propose an intelligent soft robotic system for efficient and gentle strawberry harvesting. The system combines an AI-powered computer vision module to detect ripe strawberries, a soft silicone-based robotic arm to handle fruit without damage, and a data-driven control method for smooth, adaptive movement. An adjustable ground vehicle supports flexible field navigation. Initial results show a harvest success rate of 66.7% and an average speed of 240 strawberries per hour, demonstrating the potential of soft robotics for safer and more effective automated harvesting
Embedded two-phase cooling in an additively manufactured stator prototype for a novel high-power-density electric motor concept
No full textElectrification of transportation in the aviation industry is challenging in part due to the high power densities necessary for propulsion using electric motors. A commercial, narrow-body aircraft would require electric motor systems having \u3e12 kW/kg power density, over twice the current state-of-the-art. One major limitation to increasing power density are limits on the operating temperature. Electric motor windings, which are wrapped in insulation, produce the majority of the heat in the motor. Positioning the coolant closer to the windings so as to decrease the overall thermal resistance between the heat source and sink is therefore a promising route toward enabling higher power densities. In this study, an additively manufactured stator subsection prototype with embedded microchannels is used to demonstrate two-phase cooling at different mass flow rates of R1233zd(E). Compared to single-phase cooling, utilizing two-phase flow provides higher heat transfer coefficients, which have increasing importance on reducing the overall resistance when the coolant is embedded close to the heat source, as well as offering a nearly isothermal coolant at the saturation temperature independent of mass flux. This prototype test section, which has been demonstrated for continuous operation at 30.4 A/mm2, is experimentally characterized at five flow rates between 0.33 g/s and 0.83 g/s. The average coil temperature is demonstrated to be insensitive to mass flow rate, as is desired for practical operation, owing to the high effective heat capacity rate when operating in the two-phase regime. Instrumentation of the test section with wall-embedded thermocouples enables decomposition of the total coil temperature rise into the conductive and convective thermal resistance components. The incorporation of two-phase flow reduced the convective thermal resistance by 77 %. Thermal models for each of these resistance components are developed to validate experimental findings, and further, to allow performance prediction in context of up-scaling to the full motor assembly and higher operating powers
Degradation Mechanisms and Microstructural Performance of 3D-Printed Engineered Cementitious Composites with Yellow River Sand under Chloride Ion Wet-Dry Cycles
No full text3D printing of Engineered Cementitious Composites (ECC) is an emerging, cutting-edge construction technology that enables layer-by-layer fabrication without the need for formwork or steel reinforcement. ECC exhibits superior tensile strength and crack resistance compared to conventional concrete. However, the durability of composite structures, especially in marine environments exposed to harsh conditions such as sulfate and chloride ions, remains a concern. This study investigated the performance of cast and 3D-printed specimens under chloride ion wet–dry cycles (0, 5, 10, 15, 20, 25, and 30 cycles) and utilised sustainable Yellow River sand (YRS) as a partial replacement for quartz sand to reduce material costs. Results showed that the compressive strength of both cast and 3DP-ECC specimens was highest in the Z direction. Among them, the R25 cast specimens exhibited better strength properties, starting at 34 and 32 MPa, respectively, and decreasing to 22 and 23 MPa after 30 cycles of chloride exposure. In comparison, compressive strength in the Y- and X-directions decreased by 20% and 23%, respectively. Scanning Electron Microscopy (SEM) images of cast ECC revealed a dense and relatively uniform microstructure, with well-bonded phases between the matrix and the aggregates. The interfacial transition zone (ITZ) between the cement paste and aggregates appeared smooth, indicating strong bonding with minimal porosity. This study highlighted that incorporating Yellow River Sand as a partial replacement in 3D-printed ECC not only enhances sustainability and reduces material costs but also maintains satisfactory mechanical performance, particularly at the 25% replacement level, under chloride ion wet–dry cycles
A Unified Rheological Parameter for Concrete: Application of the Shear Work Index in Flowability Optimization
No full textAdequate flowability is crucial to ensure proper homogeneity, mechanical properties, and durability of hardened concrete. A new parameter called the Shear Work Index (SWI), which combines yield stress and plastic viscosity, was recently proposed by the authors to evaluate concrete flowability. Factors that can influence SWI are analysed in this paper. Application methods of SWI are demonstrated through case studies involving the evaluation of rheology-modifying materials, the selection of the optimal manufactured sand replacement ratio in mixed sand, and the determination of concrete vibration time. The findings highlight the effectiveness of SWI as a comprehensive parameter for optimising concrete mix design and guiding concrete construction
Simultaneous topology optimization of two hydraulically interconnected porous flow layers in cold plates
No full textCold plate topology optimization is a focus area of research in thermal management, often approached with simplified two-dimensional models to maintain the low computational costs needed for iterative design. However, embracing higher dimensionality in optimization can yield significant performance enhancements, as exemplified by cold plate architectures like manifolded microchannels. In this study, we present a novel 2.5D topology optimization framework tailored to two-flow-layer manifold cold plates, leveraging the homogenization approach to topology optimization. Under this framework, multiple stacked flow layers are simultaneously optimized within a 2D stack while considering local mass and energy exchange between them, enabling the design of intricate 3D flow geometries with the computational efficiency of 2D simulations. The mass and energy exchange between the layers is governed by the optimizable inter-layer flow resistance. This approach is demonstrated for a test case with two coupled flow layers between enclosing solid substrates heated from their external surfaces. The homogenization approach is used to define the local design variables in these layers based on the physical porosity of microstructures (viz., square pin-fins) and the inter-layer coupling within computational cells. A multi-objective cost function, encompassing total pressure drop and thermal resistance, guides the optimization of the microstructure distribution in each layer, resulting in a Pareto front of designs illustrating the balance between these two competing objectives. Full-scale, high-fidelity 3D flow simulations were performed on the topology-optimized two-flow-layer cold plate to validate results from the homogenized 2D simulations. The calculated flow fields showed good agreement between low-cost 2D simulations and high-fidelity 3D simulations, demonstrating the accuracy of the approach. The study provides valuable insights into the topology optimization of multi-layer cold plates, highlighting the potential for enhanced performance via higher dimensionality, as well as manufacturability through the homogenization approach
Individuals’ Experiences of Care Partner Involvement in Heart Disease Management: A Pilot Study
No full textIntroduction: Heart disease impacts both those diagnosed and their families, often due to lifestyle modifications that can alter family dynamics. While existing literature focuses on men and married individuals, understanding care partner involvement for both men and women independent of marital status is important, given gender disparities in heart disease experiences, caregiving roles, and widowhood rates. We explored differences in characteristics of men and women with heart disease, with and without a care partner. Additionally, we explored involvement of care partner beyond spousal relationships. We further examined gender differences in these experiences. Method: Cross-sectional Prolific survey pilot data of persons with heart disease (N=186) were analyzed. We used Chi-square tests and t-tests to test participant characteristic differences by care partner status and care partner involvement differences by gender. Results: Over half of participants reported having a care partner. Those with a care partner were more likely to be married, and more likely to have participated in cardiac rehabilitation, with their participation occurring, on average, two years more recently than those without a care partner. Most primary care partners were spouses and female. Care partners were most often reported to be involved in helping maintain a healthy diet. Discussion: Care partner involvement is prevalent among persons with heart disease, with some gender differences in these experiences. Future research should explore how to best integrate care partners into disease management to benefit both persons with heart disease and their care partners
Steel Joist and Joist Girder Design
No full textThis course starts with the basics of steel joist design, terminology, SJI (Steel Joist Institute) load tables, and special loading conditions, but then will take a closer look at many details on the construction of a joist that you probably haven’t seen before. You will learn what the extra clips and bars are attached to joists and what their purposes are. This will be a picture rich presentation