1,720,997 research outputs found
Dynamic simulation of future integrated energy systems
Get PDFThe building sector is responsible for a large part of the world's total energy use. More than half of building energy use is needed for space heating, domestic hot water heating, and space cooling. Thermal energy supply systems are used to cover these thermal energy demands and are an integral part of new buildings and neighborhoods. These systems are becoming increasingly more complex due to the inclusion of renewable energy sources and thermal storages. Advanced simulations are required to analyze the design and the operation of these complex systems in detail and are thus an important part of the transition to new and improved building energy systems.
In this work, component and system models for thermal energy supply systems were developed in the modeling language Modelica. Numerical efficiency was an important part of the development process because the aim was to analyze long periods of time. In addition, the different requirements for simulation and optimization had to be considered during model development. Detailed description of all the developed Modelica models are given in this thesis. The models were used for dynamic simulations with Dymola as well as dynamic optimizations with JModelica.org, of which the latter proved to be more challenging. The optimization approach is therefore also described in detail in this thesis.
The design and the operation of two case study systems were analyzed in this work: 1) an existing integrated heating and cooling system at Vulkan, Oslo and 2) a planned local district heating grid at Brøset, Trondheim. The main components of the integrated heating and cooling system at Vulkan were heat pumps, plate heat exchangers, flat plate solar collectors, water storage tanks, ice thermal energy storage, and borehole thermal energy storage. The system supplied a total floor area of 38 500 m2 and is described in detail in this thesis. The main components of the local district heating grid at Brøset were a heat central, distribution pipes, and customer substations. The system was assumed to supply a total floor area of 178 000 m2 and the different system design concepts that were analyzed are described in this thesis.
The main focus of this work was the case study system at Vulkan. The simulation results showed that the current operation of this system might be unsustainable due to an unbalanced long-term storage. Sustainable operation was possible in the simulations by increasing the number of solar collectors or the amount of imported heat from the district heating grid. The optimization results showed that variable setpoints for the heating and cooling supply temperatures could reduce the electricity use of the system. However, this would require the implementation of an advanced control system. The installation of larger storage tanks combined with optimal control was also investigated. It was shown that this combination could reduce the electricity costs of the system. However, the savings were not large enough to make an installation seem profitable with the current pricing scheme. Higher peak load tariffs and/or an increased variability of the electricity price might change this conclusion in the near future.
The analyses of the different system design concepts for the local district heating grid at Brøset showed that low-temperature grids were more environmentally-friendly than high-temperature-grids. This was mainly due to lower heat losses in the grid and the ability to include waste heat sources. The diameters of the district heating distribution pipes were shown to be important for the heat losses of the pipes and the required pumping power.
Several Modelica libraries with similar component models as the ones presented in this thesis are available. However, the system model development and the dynamic optimizations proved to be the most challenging tasks in this work. These tasks require a rather high level of user experience, but are expected to be increasingly important in the near future. This prediction is supported by the coordinated efforts that are currently going on in the IBPSA Project 1, which has a scope similar to the one of this thesis
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
- …
