1,720,983 research outputs found
Highly robust superhydrophobic coating of aluminum 2024-T3 alloy for corrosion mitigation, deicing, and self-cleaning of aircraft
No full textThesis (M.S.)-- Wichita State University, College of Engineering, Dept. of Mechanical EngineeringMetals and alloys are used extensively because of their characteristics, including high
strength, ability to bear heavy loads and stress, ductility, machinability, and so on. Metals and
alloys are subject to corrosion when they come in contact with an aggressive environment.
Among all the metals and alloys, aluminum is primarily used for various applications under
aggressive atmospheric conditions, which result in its loss of metallic luster, changes in the
dimensions of the aluminum, and its loss of strength. Many techniques have been used to
minimize the corrosion of aluminum and its alloys, one of which is to employ a plasma surface
cleaning treatment. Using this technique to fabricate the aluminum surface as a
superhydrophobic (SH)-coated surface is the ultimate goal, whereby the coated surface becomes
a water-fearing surface, can resist corrosion for a longer period of time, and can be applied as the
best surface for icing conditions. Heat treatment was executed on the surface to make the SH
coating highly robust.
The corrosive behavior of Aluminum 2024-T3 alloy was tested using a 3.0% sodium
chloride (NaCl) solution, which is an aggressive solution. The resulting behavior was
investigated by means of contact angle measurement, linear polarization, electrochemical
impedance spectroscopy (EIS), Fourier transform-infrared (FTIR) spectroscopy, Vickers
microhardness, and salt soaking. Additional tests—tape adhesive, deicing, freezing time, supercooled water, and self-cleaning—were performed to show that the surface coat remains
superhydrophobic schematically. It was discovered that the plasma surface cleaning treatment
increases the adhesiveness between the substrate and the top coat, which results in the coated
surface remaining superhydrophobic for a long period of time. The corrosion rate of the surface
is also reduced, which provides a double benefit
Development of machine learning models for improving and achieving target fiber diameter of electrospun nanofibers
No full textThesis (Ph.D.)-- Wichita State University, College of Engineering, Dept. of Mechanical EngineeringElectrospinning is a widely recognized technique for fabricating nanofibers with tailored properties, essential for applications in fields such as tissue engineering, drug delivery, filtration, energy storage, and sensors. However, the complexity of the electrospinning process, with its various experimental process parameters poses significant challenges in achieving consistent fiber diameters. This study explores the option of integrating machine learning (ML) algorithms to accurately predict and precisely control fiber diameters, thereby enhancing the efficiency of the electrospinning process. The study includes a comprehensive review of current ML applications for electrospun nanofibers. Predictive ML models were developed to train a dataset compiled from published research scientific sources, with eXtreme Gradient Boosting (XGB) achieving a coefficient of determination (R²) value of 0.93 and root mean square error (RMSE) of 127.76 nm on polyacrylonitrile (PAN) nanofibers and an R² value of 0.94 with an RMSE of 79.89 nm on polyvinyl alcohol (PVA) nanofibrous scaffolds for tissue engineering applications. In addition, a broader dataset containing 3000 data points across a range of polymers, solvents, and process parameters was used to refine predictive ML models further. Among the various ML models, the XGB model demonstrated superior performance, achieving an R² value of 0.94 with an RMSE of 275.02 nm. Experimental validation with electrospun polystyrene (PS) nanofibers confirmed the robustness of these predictions, showing strong alignment between predicted and measured fiber diameters. Process optimization was performed using a Genetic Algorithm (GA), achieving target fiber diameters between 100 nm and 4000 nm with low fitness errors. This integrated approach achieves a near-perfect correlation (R² = 1.00) between target and predicted fiber diameters across diverse electrospinning conditions, reducing dependency on trial-and-error experimentation and enabling scalable, data-driven nanofiber fabrication tailored to specific applications
Correction to: Studies on de-icing and anti-icing of carbon fiber-reinforced composites for aircraft surfaces using commercial multifunctional permanent superhydrophobic coatings
No full text© Copyright 2020 Elsevier B.V., All rights reserved. Correction is Open Access. The original article can be found online at https://doi.org/10.1007/s10853-020-05459-9.In the original article, the name of author A. Khadka was misspelled. It is correct here
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Corrosion mitigation of metals and alloys via superhydrophobic coatings with plasma surface and heat treatment processes
No full textClick on the DOI to access this article (may not be free).Many industries utilize metals and alloys because of their exceptional properties, including high strength, conductivity, load-bearing capability, ductility, creep, and fatigue resistance. Among the metals and alloys, aluminum and its alloys are mostly subject to corrosion when encountering under severely adverse conditions that result in oxidation, failure of metallurgic luster, modifications in the sizes, strength, and changes in other physical and chemical properties. In this study, we produce superhydrophobic coated (SHC) aluminum 2024 alloy (AA2024) substrates for corrosion mitigation using a combination of physical and chemical modification processes. Plasma surface and heat treatment have been utilized for physical modification by forming nano-scaled roughness on the AA2024 substrates. To improve the surface hydrophobicity, chemical modification was achieved using low surface energy coatings. The corrosion behavior of plasma surface and heat-treated superhydrophobic coated (PSH-SHC) AA2024 substrates were evaluated by immersing into a 3.0% sodium chloride (NaCl) solution. The domination of plasma surface and heat treatment on the surface roughness, wettability, and corrosion resistance of the prepared AA2024 substrates was examined by applying water contact angle (WCA) measurements, potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), and salt soaking tests. The test results confirm that the PSH-SHC AA2024 substrates remain superhydrophobic with a WCA ? 168° for an extended period of time with superior corrosion resistance in harsh environments. The WCA measurements slowly reduced from 168° to 157° after immersion in the 3.0% NaCl solution for 30 days. It demonstrates that the plasma surface and heat treatment mechanisms drastically enhanced the adhesive strength between the AA2024 substrate and the superhydrophobic coatings. The PDP and EIS results also showed that the corrosion rates of the 8H-PSH-SHC AA2024 substrate were undesirably low and raised with expending immersion time in the 3.0% NaCl solution. It is concluded that techniques applied in this study are found to be promising and critically important for a longer service time of the metals and alloys for broader industrial applications to mitigate the corrosion problems
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
- …
