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Modeling framework for systems analysis of the petrochemicals industry using network models
Get PDFRecent technological advancements in hydraulic fracturing and horizontal drilling have lead to a substantial increase in the production of crude oil and natural gas in the United States. Unconventional oil and gas sources, such as shale formation are now economically favorable to exploit, and thus, shale gas has dominated natural gas production. In contrast to conventional sources, shale gas typically contains a high concentration of natural gas liquids (NGLs), which have to be removed to produce consumer-grade, dry natural gas. Therefore, the rapid increase in shale gas production has lead to an abundance of low-cost NGLs available for use, either directly as fuels or primarily as feedstock for petrochemicals manufacturing. The increasing production of shale gas, and consequently of natural gas liquids (NGLs), provides unique opportunities to expand the U.S. chemical industry, leading to questions about how to best use these resources. It is, thus, essential to assess any change before it is implemented in order to make prudent decisions, especially considering the magnitude of capital investment needed to make such changes or the potential disruptions that may occur. A common approach for determining the competitiveness of a new process relative to existing processes that generate the same product, or for comparing alternative new processes with one another, is to employ a techno-economic analysis. Despite being effective in comparing different processes on a consistent basis, this approach does not account for follow-on effects that may be caused by inserting a new process into the existing industrial ecosystem. These effects can often be substantial and could significantly alter the conclusions of simple techno-economic comparisons when taken into consideration. A systems approach that considers the entire petrochemicals industry is thus needed. For that reason, the overreaching goal of this dissertation is to solve the problem of optimally designing the petrochemical industrial network by developing and implementing a modeling framework that can determine the optimal industry configuration, i.e. the optimal technology selection and utilization as well as material flows, under one (or more) objective(s) and supply and demand limitations. In Part I, I present a new decision-making framework for analyzing the chemical manufacturing and refining industry in the United States by developing and implementing network models of the industry. First, I introduce the motivation for modeling the industry with network models and explain why they can effectively represent the system. Then, I provide an extensive literature review, followed by the presentation of linear network models, a relatively easy model to develop and solve that has been the go-to approach in literature. A comprehensive linear programming (LP) formulation of these models is shown, along with a discussion regarding their limitations. To deal with such limitations, I propose a new type of network models with variable-costs, along with an efficient way of solving such models, which are significantly more computationally complex. This renders the problem nonlinear and potentially discontinuous. I presented a nominal way to formulate the problem as a mixed-integer, nonlinear program (MINLP), which is significantly harder to solve. For this reason, I also propose a decomposition scheme as an efficient alternative to dealing with this problem, based on successive linear programming (SLP) and a cost-propagation algorithm. All the different models are compared with each other in terms of accuracy and computational efficiency, first on prototype networks, and then on industry-wide applications. In Part II, I implement the framework to analyze and assess competing pathways to utilize newly available NLG resources, particularly ethane and propane, the two biggest NGL components. First, I evaluate the impact of a potential, new catalytic dehydrogenation technology for converting ethane to ethylene, and then I evaluate potential, new catalytic oligomerization processes for converting ethylene to 1-butylene and to 1-octene. For each new technology evaluated, I determine the production level of the technology in the optimal industry network. By doing this over a wide range of net process cost points, a maximum adoption cost (the net process cost beyond which the technology would not be adopted into the optimal configuration) can be identified, and its sensitivity to the assumed product yield determined for each new technology studied. Scenarios in which the ethane supply is constrained to current values, and in which it is unconstrained, are considered. Similar studies are also performed for propane, where a new catalytic dehydrogenation process for converting propane to propylene was assessed and compared to propane exports. In Part III, I expand the framework to include more than one objectives, by developing and using multi-objective network models of the petrochemical industry that minimize both production cost and carbon loss across the industry. The model is first solved for each objective separately, and then the weighted sum and ϵ-constraint methods were employed to obtain the Pareto-optimal set of solutions. Moving along the Pareto front towards the minimum carbon loss point causes a number of structural changes in the industry network, which are presented and discussed.Chemical Engineerin
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
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