1,720,956 research outputs found
Electrical characteristics of dielectric barrier discharge / Tay Wee Horng
Full text linkThe industrial application of the dielectric barrier discharge (DBD) has a long tradition. However, the lack of understanding of some of its fundamental issues, such as the stochastic behaviors, is still a challenge for DBD researchers. In this project, considerable efforts to understand the fundamental aspects of DBD have been made. The aim of this work is to study the electrical characteristics of DBD to determine a suitable condition for utilization of the device for applications. Several diagnostic tools such as high-voltage probe, resistive current, charge measurement, and high-speed camera imaging were employed for the investigation. In order to study the electrical behaviors of DBD, the experimental work was carried out in two parts: current pulse amplitude statistical studies and the energy investigation. For the pulse amplitude statistical studies, the stochastic variation of the current pulse amplitude has been analyzed by the statistical method. The stochastic behavior of the discharge current amplitude has been compared with a proposed empirical equation of the distribution pulse height. This proposed statistical function is found to be in good agreement with the experimental discharge pulse amplitude variation for discharges with varying space gaps. This empirical equation successfully predicts the existence of two discharge regimes, which were observed from the experimental results. For the energy investigation, the DBD dissipation energy was studied experimentally and numerically. A dynamic circuit model constructed with Matlab Simulink accurately simulated the discharge energy of DBD. The surface resistance introduced in this electrical model represents the average effect that effectively accounts for the resistance encountered by the charges between the discharging and non-discharging regions on the dielectric. The expanded QV Lissajous can be reasonably explained by the fact that the total energy is summed by the energy of the DBD discharge and the energy consumed by the spreading
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charges on the dielectric surface. By having the experimental results accurately fitted with the simulated results from the model, the efficiency of discharge can be obtained from the electrical modeling. The efficiency of the DBD has been found to be higher with a smooth surface compared to a rough surface. The efficiency is reduced when the applied voltage is increased. Based on the energy and current pulse amplitude distribution model, the DBD system can be designed according to the desired condition by controlling the required energy efficiency and pulse height distribution
Numerical Simulation for Dehydration of Natural Gas using Joule Thompson Cooling Effect
No full textAbstractIn this study, the potential of Joule Thompson cooling effect for natural gas dehydration was studied using numerical simulation method. Population balance model (PBM) was used to simulate the non-equilibrium water condensation process. Meanwhile, empirical nucleation model and diffusion growth model were taken under consideration in order to predict the onset of the water nucleation and the non-equilibrium mass transfer rate. The simulation condition was set at 78% of CO2content,feed pressure of 71bar and temperature of 300K. The Joule Thompson effect has been validated with the experimental data. The non-equilibrium results were then compared with the equilibrium results in order to investigate the pressure drop required for the water nucleation. Results showed that,alarge homogeneous nucleation of water occurred at the pressure drop larger than 30bar. This has resulted in an extremely high condensation rate for the vapor in the natural gas under high pressure drop. Hence, the transition of non-equilibrium to equilibrium can be achieved within 5 milliseconds condensation time, indicating the possibility of Joule Thompson cooling effect in high efficient natural gas dehydration
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
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