1,721,115 research outputs found
Quynh Tran: Varjo ja viileys
No full textArvio teoksesta Quynh Tran: Varjo ja viileys (Skugga och svalka). Suom. Outi Menna. Teos & Förlag 2021. 257 s.nonPeerReviewe
Driven primary regulation for minimum power losses operation in islanded microgrids
Full text linkThe paper proposes an improved primary regulation method for inverter-interfaced generating units in islanded microgrids. The considered approach employs an off-line minimum losses optimal power flow (OPF) to devise the primary frequency regulation curve’s set-points while satisfying the power balance, frequency and current constraints. In this way, generators will reach an optimized operating point corresponding to a given and unique power flow distribution presenting the minimum power losses. The proposed approach can be particularly interesting for diesel-based islanded microgrids that face, constantly, the issue of reducing their dependency from fossil fuels and of enhancing their generation and distribution efficiency. The Glow-worm Swarm Optimization (GSO) algorithm is selected as a key heuristic tool for solving the optimization problem. The main program is carried out in Matlab environment. A case study with a parametric analysis is implemented and all results are assessed and compared with the conventional droop control method to show the effectiveness of the proposed method as well as the improved reliability of the system
Minimum power losses by using droop coefficients regulation method with voltage and frequency constraints in islanded microgrids
No full textIn this paper, a droop coefficients regulation methodology is proposed for an islanded microgrid to optimize the power losses. Based on the P-f and Q-V relations to adjust the droop coefficients at every loading condition, the optimized operating set point generates minimum power losses operation while satisfying the constraints of voltage and frequency limitation. A 9-bus case study is here implemented to show the effectiveness of this new approach as well as the improved operation quality of the system
Phytochemical profiling of Echinacea Genus: A mini review of chemical constituents of selected species
No full text<p>Truong Thi Diem Quynh, Tran Thi Diem Thuy, Pham Vu Khiem, Nguyen Viet Thien, Ha Hai Anh</p>
Effects of Mobile Commerce on Customer Usage Intention: An Empirical Study in Viet Nam
Full text linkMobile commerce has been rapidly developing in the recent years and it plays an important role in many aspects. In Vietnam, there are limited studies researching mobile commerce and its impacts. Therefore, this study aimed to discover the factors that influence the intentions of Vietnamese consumers to use mobile commerce.
Based on the theoretical background, the research model and its hypotheses were tested and developed by collecting the data from a questionnaire survey. This research provides thirteen hypotheses to determine the main factors that contribute to intention to use of mobile commerce system. Based on the traditional Technology Acceptance Model (TAM), the research included more dimensions into the study including trust, cost and playfulness factors.
The results are based on the data analysis collected from 235 Vietnamese participants through a face-to-face, a paper survey and online questionnaire. The result showed that the intention to use dominantly affected the mobile commerce usage in this model. Perceived usefulness and perceived ease of use in this paper did not affect directly to intention to use, however, PU directly affected mobile commerce usage and PEOU indirectly affects intention to use through perceived playfulness. Intention to use has direct effect on perceived trust and perceived playfulness while mobile commerce usage has direct influence on perceived playfulness and perceived cost. Finally, it is hoped that this study could provide the outcomes to help further research to have a better insight into Vietnamese consumer behavior as well as business players to develop better strategies in mobile commerce market
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
Additional knowledge respecting taxonomy of the social wasp genus Ropalidia (Hymenoptera: Vespidae: Polistinae) from Vietnam, with new records of three species and an updated key to species
No full textBui, Hoa Thi Quynh, Tran, Ngat Thi, Bozdoğan, Hakan, Nguyen, Lien Thi Phuong (2020): Additional knowledge respecting taxonomy of the social wasp genus Ropalidia (Hymenoptera: Vespidae: Polistinae) from Vietnam, with new records of three species and an updated key to species. Zootaxa 4722 (1): 34-40, DOI: 10.11646/zootaxa.4722.1.
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