1,722,161 research outputs found
Circuit models and simulations of surge attentuation on HV transmission system
No full textTransient overvoltages occur in high voltage systems due to the operation of circuit breakers or disturbances such as faults and lightning strikes. These overvoltages will propagate through the system as surge voltages. The mechanism of the propagation is governed by two partial differential equations (telegraphers' equations). The surge will be attenuated and distorted due to energy losses when it travels along the system. The major energy losses under surge conditions are the ohmic and the corona losses. The ohmic losses in the conductor, the earth return and the cable sheath are frequency dependent. This thesis describes a method to develop an equivalent circuit model to cater for the variation of these ohmic losses in a single phase tranmission system during the surge period. Circuit elements of the model are determined using the skin depth theory and the accuracy of the approximation is dependent on the number of branches in the circuit model, the geometry of the system and the frequency bandwidth of the incoming surge. Investigations are caried out for steady state and transient response of the circuit models. The results are used to compare with the analytical derivations (Bessel functions, Carson's formula) and the field approach (`PE2D' finite elment package). The corona loss is dependent on the system voltage. It is modelled by another circuit network consisting of a capacitor and a resistor connected in parallel. The dynamic values of the circuit elements are obtained using Peek and Skilling's equations which are inserted across the geometrical capacitance when the system voltage exceeds Vco and dV/dt> 0. The simulation of surge propagation is carried out using discrete `pi' circuit networks. Long transmission lines are divided into short sections and each section is represented by an equivalent `pi' circuit network. The complete transmission system is reconstructed by cascading these `pi' networks together and the line losses are represented by using the appropriate circuit models. The simulated surge voltages using different transmission line models are presented and compared with published data of field tests. A comparison between simulations using the circuit model and single frequency skin effect (Bessel functions) and earth return (Carson's formula) correction is presented. The method is extended to simulate the surge propagation in a cable system under fast transients. Finally, a circuit model is developed for a ferrite choke surge attenuator and incorporated into the transient analysis program to investigate the amount of attenuation introduced by the choke.</p
Jing Tong Yu Shu, a traditional Chinese medicine, suppresses IL-1β and IL-6 gene expressions in macrophages, and alleviates endometriosis
Full text linkPurpose: To evaluate the effect of a traditional Chinese medicine, Jing Tong Yu Shu (JTYS) on endometriosis in a rat surgical model. Methods: Endometriosis was induced in 40 female rats. The rats were randomly divided into 4 groups: three JTYS groups given different doses of the drug, and a saline group. After four weeks of treatment with JTYS, the volume of the endometriotic explants was measured, and the levels of IL-1β and IL-6 in peritoneal fluid and serum were determined by enzyme-linked immunosorbent assay (ELISA). The production of cytokine IL-1β and IL-6 by peritoneal macrophages was also measured for each group. Results: JTYS treatment brought about regression of implants and inhibition of IL-1β and IL-6 production in a dose-dependent manner, with high-dose JTYS eliciting 66.76 % reduction in mean endometriotic explant volume. Plasma and peritoneal fluid levels of IL-1β and IL-6 were significantly lower in the high-dose JTYS group than in the saline group (p < 0.05). However, JTYS treatment significantly inhibited IL-1β and IL-6 production in peritoneal macrophages (p < 0.05). Conclusion: These results suggest that JTYS treatment leads to regression of endometriotic lesions in rat. Thus, JTYS has the potential to be developed into a new drug for the treatment of endometriosis. Keywords: Endometriosis, Interleukins, Traditional Chinese medicine, Jing Tong Yu Shu Macrophage
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
Supplemental Material - Independent Prognostic Factors and Nomogram Prediction of Cancer-Specific Survival in Postoperative Patients With Spinal Cord Astrocytoma
No full textSupplemental Material for Independent Prognostic Factors and Nomogram Prediction of Cancer-Specific Survival in Postoperative Patients With Spinal Cord Astrocytoma by Yang Wang, Jianhang Jiao, Tong Yu, Zhonghan Wang, Weibo Jiang, Xuqiang Gong, Han Zhang, Jing Yue and Minfei Wu in Global Spine Journal</p
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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