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Enhancing Distribution System Situational Awareness Using Smart Meters
Full text linkThe increasing levels of distributed energy resources (DERs) penetrations can resultin significant operational challenges at the power distribution level. This calls for enhancing distribution system level situational awareness to assist distribution system operators in making the best operational decisions under disturbances. In this work, enhancing situational awareness implies extending the visibility of the power distribution system beyond the substation. Extensive roll-out of smart meters allows utilities to collect significantly more real-time data, which can be leveraged to develop new monitoring tools. This work uses smart meter data available at the grid-edge to enhance the power distribution system’s situational awareness. Specifically, within a three-level SA framework that includes perception (level-1), comprehension (level-2) and projection (level-3), this work makes the following contributions with regard to level-2 SA tools. First, we evaluate the impacts of inadequate end-use load models and associated nonlinearities on system state variables. To this end, we compare the harmonicdistortions due to a detailed and approximated constant current model for nonlinear residential loads on North American residential distribution systems. North American residential distribution system with split-phase configurations is usually modeled as a single-phase equivalent model. The harmonic distortion analysis with the single-phase equivalent network model is found to underestimate the current distortions and overestimate the voltage distortions. The analysis with three different approximate models for an unbalanced split-phase residential distribution system shows that the balanced split-phase residential distribution system is a reasonably accurate representation of the unbalanced split-phase residential distribution system. Second, we evaluate the impacts of measurement non-idealities on system-level states. To this end, we evaluate the effects of the following smart-meter attributes: measurement interval, time synchronization error, meter bias, and measurement noise on distribution system voltage and total loss. The analysis shows that temporal aggregation of smart meter data can alter the data distribution. The time synchronization error for household smart meters does not follow Gaussian distribution and the incomplete data reporting creates uncertainty in system-level states. Third, to enhance the real-time SA of distribution systems, we develop a state estimation algorithm that provides an integrated monitoring of primary and secondary feeders. This approach enables us to use measurement information from the smart meters at the grid-edge by appropriately modeling the secondary feeder beyond the distribution-level service transformer. The accuracy of the state estimation algorithm is tested for different levels of measurement and model inaccuracies and for non-gaussian measurement error distributions. Finally, to enhance distribution-level SA during outage conditions, we develop a spectral clustering-based outage detection algorithm that is simple to implement and solves efficiently by leveraging the smart meter outage notifications and forecasted load data. In conclusion, this thesis highlights and develops tools to effectively use smart meters to enhance distribution-level SA beyond primary feeders to the customer level
Mathematical Modeling and Capacity Fading Study in Porous Current Collector Based Lithium Ion Battery
Full text linkLithium ion (Li-ion) batteries are primary energy storage devices especially in electronic gadgets, electric vehicles and for stationary storage of intermittent renewable energy. These applications demand durable Li-ion batteries with higher energy density. Energy density can be increased either by finding novel electrode materials or by modifying the existing design of the battery. The electrode materials or modified design should not only increase energy density, but also should control the capacity fading of the battery. In this work, existing mathematical model of Li-ion battery was adjusted in the case of the porous current collector. The discharge performance and capacity fading of the porous current collector based Li-ion battery was compared with non-porous current collector Li-ion battery. The electrode averaged model (EAM) was used to simulate the discharge performance of the battery. The capacity fade was compared by comparing the film growth, change of initial electrode state of charge (SOC) and change in solid phase diffusion coefficient with cycling. Both simulation and experimental results have shown the porous current collector based Li-ion battery achieves greater than the theoretical specific capacity of electrode active materials for the first few cycles of operations. In this work, Lithium titanate was considered as an electrode active material which has a theoretical specific capacity of 175 mAh/g. Simulation and experiment have predicted specific capacities of 238 mAh/g and 235 mAh/g respectively in the case of the porous current collector. Simulation result showed the porous current collector Li-ion batteries reaches the end of useful life after 100 more cycles than the non-porous current collector batteries under similar conditions of operation
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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