1,720,969 research outputs found
Frequency domain analysis of FCL equipped transmission systems for protection applications
No full textThis paper presents a method for calculating electromagnetic transient scenarios for transmission systems equipped with fault current limiters (FCL). Transmission systems are represented in the Laplace s-domain and current limiter elements are modelled as current sources. The method is demonstrated for multi-conductor systems. The main advantages of the proposed method are its accuracy and its adequacy for testing protection algorithms. � 2004 IEEE
Comparison of transmission tower models for evaluating lightning performance
No full textThis paper focuses on the representation of tall metallic structures, such as power line towers, by means of vertical transmission line segments. Some of the most common tower models are tested here. The differences between the single vertical line models and the vertical multi-conductor ones are demonstrated through the comparison with a field experiment. � 2003 IEEE
Analyzing transients on multiconductor lines with corona
No full textThis paper describes a line model which is intended for analyzing transients on multi-conductor lines with corona. This model is based on the method of characteristics from the theory of partial differential equations. It accounts for the facts that line modes depend on the conductor voltages and that the modes do not superpose linearly. The proposed model is applied in the simulation of a field experiment Comparisons are made between simulated and measured waveforms. Also a comparison is made against a simulation with a single-phase line model. The results attained with the model proposed here are very encouraging. Zapotitlán2004 IEEE
Modeling methodology for NPC's using Interpreted Petri Nets and feedback control
No full textPower demand is currently growing in Mexico at an annual rate above 5 %. The actual transmission system has to increase its power transfer capacity without compromising the power supply and the system integrity. Power protection engineers are thus resorting more to single pole tripping schemes with automatic re-closings. Relay coordination tasks are thus becoming increasingly complex. This article presents a methodology by which, through time domain computer simulations, one can establish proper relay settings for such a highly demanding scenario. " 2007 IEEE.",,,,,,"10.1109/NAPS.2007.4402281",,,"http://hdl.handle.net/20.500.12104/42884","http://www.scopus.com/inward/record.url?eid=2-s2.0-50249187837&partnerID=40&md5=47051648b29bcd4e652711d7be53d171",,,,,,,,"2007 39th North American Power Symposium, NAPS",,"2
The state and security in Mexico: Transformation and crisis in regional perspective
No full textA switch model previously proposed in references [1], [2| and [3] for power electronics applications is adopted here to simulate electromagnetic transients in power systems. The switch model is in the generic form for EMTP analysis, consisting of a constant conductance element and a current source in parallel. Switch operations are simulated by means of the current source only; therefore, at these operations, the conductance matrix representing the power system under study is maintained constant throughout an entire simulation. It is shown in this paper that the switch model is very general, it is efficient and numerically very stable. " 2003 IEEE.",,,,,,"10.1109/PTC.2003.1304646",,,"http://hdl.handle.net/20.500.12104/45307","http://www.scopus.com/inward/record.url?eid=2-s2.0-84861512083&partnerID=40&md5=e8489bac47849997a943a1b2725dc2c4",,,,,,,,"2003 IEEE Bologna PowerTech - Conference Proceedings",,"78
The transient simulation of a power network with invariant admittance matrix
No full textA switch model previously proposed in references [1], [2| and [3] for power electronics applications is adopted here to simulate electromagnetic transients in power systems. The switch model is in the generic form for EMTP analysis, consisting of a constant conductance element and a current source in parallel. Switch operations are simulated by means of the current source only; therefore, at these operations, the conductance matrix representing the power system under study is maintained constant throughout an entire simulation. It is shown in this paper that the switch model is very general, it is efficient and numerically very stable. © 2003 IEEE
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
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