1,720,953 research outputs found
Surface heated membrane with laser-induced graphene technique for membrane distillation
No full textFreshwater scarcity has become a major concern due to accelerating population growth that increases the demand from the agricultural and industrial sectors. To address the increasing freshwater supply and demand, we need to rely on different desalination techniques. However, existing technologies face challenges while treating waters having high TDS (> 70000 mg/L). Membrane distillation (MD) is a promising technology that can be used to treat hypersaline water. MD is a newer desalination technology requiring a relatively lower operating temperature and is less prone to fouling than pressure-driven processes. An efficient MD process operation requires a porous hydrophobic membrane that prevents liquid intrusion to the permeate side while only allowing water vapor to diffuse through the membrane. However, the lack of a robust hydrophobic membrane and lower energy efficiency requirements limits MD’s true potential. In this context, exploring more robust hydrophobic membranes and devising more innovative solutions to reduce the energy consumption of the MD process have been the subject of extensive research. The primary focus of the research outlined in this dissertation is to propose a novel membrane fabrication technique for developing electroconductive surface-heated membranes and integrating innovative heating techniques that can be used in MD applications.
The synthesis approach for the new membrane includes the phase inversion step to fabricate the polyethersulfone (PES) membrane substrate, followed by CO2 laser ablation. Different membrane substrates with different PES concentrations were fabricated with casting thicknesses of 700 µm. PES membrane substrates were soaked in 10 wt.% CaCl2 after being taken out of the coagulation bath. After drying, CO2 laser ablation was performed while controlling various laser parameters such as power, speed, pulse per inch (PPI), and line per inch (LPI – also known as image density). Different types of laser patterns were studied, which can give electroconductive membranes suitable for surface heating techniques integrating radiofrequency (RF) and Joule heating (JH). During the laser ablation, the polymeric surface of the membrane converts to a three-dimensional, porous conductive graphene, referred to as laser-induced graphene (LIG). Laser parameters significantly impact surface-wetting properties as these parameters control the formation of graphene on the PES membrane substrate. SEM-EDS was performed on the membranes for surface and cross-sectional morphological study, which confirmed a preserved porous structure underneath the LIG. Water contact angles were measured, which show an increase from 60° to 143.6° with increasing laser power. Raman spectroscopy and XPS analysis were also carried out to confirm graphene formation with laser ablation. The prepared LIG membrane was used in conventional VMD first before integrating surface heating. A successful VMD performance was observed, and then surface heating with RF was investigated, which eliminates MD's bulk feed heating requirement. LIG heating capability was studied first in the RF field. LIG materials showed excellent thermal response in the RF field with a maximum steady-state temperature of 500 °C. Unprecedented heating rates, as high as 502 °C/s, were observed when LIG was exposed to RF fields at 200 MHz frequency and 4.6 W power. RF parameter was further optimized for application specific to the VMD membrane module in this work , showing surface average temperature of ~140 °C. The PES-LIG membrane's mechanical and thermal properties are characterized by an investigation of its feasibility for MD application. VMD with RF heating shows permeate flux up to 13.5 L m-2 h-1 with >99% salt rejection. Cyclic thermal and mechanical stability tests and long-term VMD tests were performed, which showed stable performance of the LIG membranes. This work demonstrates a novel MD technique strategy that can potentially address challenges impeding its commercialization.
The surface heating study of VMD was further extended with the JH technique for the PES-LIG membranes. JH requires a different type of laser pattern for enhanced electrical properties of the membrane, which gives a hydrophilic LIG layer. To obtain a hydrophobic surface, PDMS-SiO2 coating was introduced with drop-casting, which gave a water contact angle of 152°, making a superhydrophobic LIG surface. JH in two modes, with direct current (DC) and alternating current (AC), was investigated. It has been found that electrode corrosion on DC JH can be overcome with AC JH. JH technique with the PES-LIG membrane prepared in this work showed successful application in VMD with permeate flux as high as 11.9 L m-2 h-1 with >99% salt rejection
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
- …
