305,119 research outputs found
EXPERIMENTAL CHARACTERISATION AND OPTIMISATION OF 3D PRINTED STACKS FOR THERMOACOUSTIC REFRIGERATION
No full textIn light of the broadening use of refrigeration in the modern industrial era and considering that conventional refrigeration fluids such as HCFCs, CFCs and HFCs are among the major causes of increased global warming, it seems necessary to implement greener and more sustainable refrigeration solutions rather than continuing to use the ordinary refrigeration methods. Literature emphasizes the need to develop simple and inexpensive acoustic refrigerator prototypes, but one major difficulty results in finding robust and reproducible setups. The following study introduces the description of an experimental and inexpensive construction of a thermo-acoustic refrigerator (TAR), aimed to convert acoustic energy into thermal energy to be used as a heat source in a refrigeration cycle. TARs operate with inert non-polluting fluids such as air, present no frictional losses and require less maintenance costs than ordinary refrigerators, and can operate with either standing or traveling acoustic waves. This work focuses on the repeatability of the setup and the robustness of the results obtained, characterizing an innovative material for the stacks production and proposing a process of optimization of the stack itself. The aim of the study is to realize a simple and economic prototype, which is also robust, easily replicable and innovative from the point of view of the choice of materials, production techniques and their optimisation process. The results concerning the gradient of temperature obtained will be analysed in order to validate the success of the experiment in terms of optimization and reproducibility
Modular Stacks for Acoustic Refrigeration: Investigating the Impact of Small Air Layers in a Modular Stack
No full textA key component in acoustic refrigerators and engines is the stack, a porous material strategically placed within a tube to harness the thermoacoustic effect. 3D printing technology for stack construction is promising due to its ability to provide accurate geometry control. One potential application is the construction of modular stacks, which could facilitate experimental studies on optimal stack length, integration of thermosensors along the stack, and printing time reduction. However, the construction of modular stacks introduces the potential for small air layers between the individual modules of the stack. This study explores the potential effects of those thin air layers between the parts of a modular stack. A numerical model of a thermoacoustic refrigerator, specifically a quarter-length resonator, was implemented based on the 1D thermoacoustic software DeltaEC. Our findings reveal that the presence of air gaps has a detrimental impact on the temperature difference achieved between the two ends of the stack. However, in the considered acoustic refrigerator configuration, small gaps below 1 mm result in a decrease below 1% of the temperature span. For the considered application and tolerances of the modular stack, the effect of the air layers could be negligible; this result opens the possibility of constructing these modular stacks. Further research is needed to corroborate these effects experimentally
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Author, publisher and bookseller : a tripartite synergy in Nigerian book industry
No full textThis work is about the roles of Author, Publisher and Bookseller in Book development in
Nigeria. The paper started by delving into the history of Book Publishing in Nigeria after
which it proceeded by defining who an author, a publisher, and a bookseller is and
expatiated on the indispensable roles of these key actors in Nigerian Book Industry and in
the emerging Information Society. Furthermore, the various constraints to book
development were identified while the paper advised on how the Book Industry can be
further promoted in Nigeria. However, the paper concluded and made recommendations
on how the Book sector can help in enhancing scholarship in the country
[Report to Chief J. E. Curry, by an unknown author #2]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
[Report to Chief J. E. Curry, by an unknown author #1]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
Mining e-mail content for author identification forensics
No full textWe describe an investigation into e-mail content mining for author identification, or authorship attribution, for the purpose of forensic investigation. We focus our discussion on the ability to discriminate between authors for the case of both aggregated e-mail topics as well as across different email topics. An extended set of e-mail document features including structural characteristics and linguistic patterns were derived and, together with a Support Vector Machine learning algorithm, were used for mining the e-mail content. Experiments using a number of e-mail documents generated by different authors on a set of topics gave promising results for both aggregated and multi-topic author categorisation
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