A three phase model for transient overvoltage studies on electrical machines during sequential pole closure

Author(s):  
J.L. Guardado ◽  
V. Venegas ◽  
E. Melgoza ◽  
K.J. Cornick
1997 ◽  
Vol 12 (1) ◽  
pp. 24-31 ◽  
Author(s):  
J.L. Guardado ◽  
K.J. Cornicki ◽  
V. Venegas ◽  
J.L. Naredo ◽  
E. Melgoza

1997 ◽  
Vol 35 (7) ◽  
pp. 139-145 ◽  
Author(s):  
Jiann-Yuan Ding ◽  
Shian-Chee Wu

The objective of this study is to quantify the effects of humic acid solution infiltration on the transport of organochlorine pesticides (OCPs) in soil columns using a three-phase transport model. From experimental results, it is found that the dissolved organic carbon enhances the transport of OCPs in the soil columns. In the OCPs-only column, the concentration profiles of OCPs can be simulated well using a two-phase transport model with numerical method or analytical solution. In the OCPs-DOC column, the migrations of aldrin, DDT and its daughter compounds are faster than those in the OCPs-only column. The simulation with the three-phase model is more accurate than that with the two-phase model. In addition, significant decrease of the fluid pore velocities of the OCPs-DOC column was found. When DOC leachate is applied for remediation of soil or groundwater pollution, the decrease of mean pore velocities will be a crucial affecting factor.


2020 ◽  
Vol 55 (3) ◽  
pp. 228-250 ◽  
Author(s):  
Andrea Cassani

Besides the introduction of multi-party elections, the sub-Saharan wave of democratic reforms of the 1990s encompassed the introduction of limits to the number of terms that a chief executive can serve. Executive term limits (ETLs) are key for democracy to advance in a continent with a legacy of personal rule. However, the manipulation of ETLs has become a recurring mode of autocratisation, through which African aspiring over-stayers weaken executive constraints, taint political competition, and limit citizens’ possibility to choose who governs. This article presents a three-phase model of autocratisation by ETL manipulation and, using new data, offers one of the first regional comparative studies of ETL manipulation in sub-Saharan Africa that rests on econometric modelling. The analysis leads to revisiting some previous findings on the drivers of ETL manipulation and highlights the relevance of other previously underestimated factors that may either discourage a leader from challenging ETLs or prevent their successful manipulation.


2008 ◽  
Vol 20 (1) ◽  
pp. 17-28 ◽  
Author(s):  
Patrícia Bertin

Scientific communication has undergone deep transformations, since the emergence of Internet. Aiming to provide further thought on the evolution of scientific communication, this paper features a historical overview of the scientific communication advances over the last twenty years through a three-phase model for the evolution of the electronic journal and the preprints services, and presents Brazilian contemporary panorama for scientific communication. The three-phase model presented in this work is an adaptation of that one proposed by Tenopir et al. (2003) to describe the patterns of journal use by scientists since 1990. The early evolutionary phase followed the emergence of the first digital journals and the creation of repositories in the Web for publishing preliminary versions of scientific literature on the author’s initiative; by that time, most academics reproved electronic publishing initiatives. From 1996 and forward, in the consolidation phase, electronic journals were commonly identical to their print counterparts; the acceptance of the electronic format began to increase, and preprint services got underway in several disciplines. The advanced evolutionary phase started with the world discussion on open access to scientific information. The comparison of the current electronic journal with that viewed by enthusiasts in the first years of the 1990s shows that some aspects still remain to be improved in electronic formal and informal communication, towards effective dissemination of scientific information.


Author(s):  
Ruhama Goussinsky ◽  
Arie Reshef ◽  
Galit Yanay-Ventura ◽  
Dalit Yassour-Borochowitz

Qualitative research is an inherent part of the human services profession, since it emphasizes the great and multifaceted complexity characterizing human experience and the sociocultural context in which humans act. In the department of human services at Emek Yezreel College, Israel, we have developed a three-phase model to ensure a relatively intense exposure to and practice in qualitative methodology. While in the first phase students are exposed to the qualitative thinking and writing, they are required in the second phase to take a Qualitative Research Methods course that includes practice. The third and final phase includes conducting a qualitative research seminar. The aim of the present article is to shed light on the dilemmas involved in implementing the three-phase model.


2013 ◽  
Vol 85 (3) ◽  
pp. 376-387 ◽  
Author(s):  
Anders Tilliander ◽  
Lage T. I. Jonsson ◽  
Pär G. Jönsson

2021 ◽  
Author(s):  
Evangelos Pompodakis ◽  
Georgios C. Kryonidis ◽  
Minas Alexiadis

This paper deals with a new line-switching method that facilitates the network reconfiguration of islanded microgrids. Its distinct features include the ability to handle network asymmetries and the minimization of the line current during the switching action. This is attained by developing a sensitive-based three-phase model predictive method to determine the operating set-points of the distributed generators (DGs) that minimize the current of the candidate line participating in the switching action. These set-points correspond to the positive-sequence powers as well as the negative- and zero-sequence currents of all DGs. Furthermore, the network constraints such as voltage limits and power limits of DGs are always satisfied. Simulations are performed in a balanced 33-bus islanded network as well as in the unbalanced IEEE 8500-node network to evaluate the performance of the proposed method.


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