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KAJIAN EKSPERIMENTAL KONVERSI ENERGI GELOMBANG DENGAN MENGGUNAKAN KOMBINASI WELLS ROTOR DAN TURBIN DARRIEUS
No full textPotensi energi yang terjadi pada kawasan pesisir pantai sangat besar, bagaimana memanfaatkan energi yang bersumber dari arus (longshore current, rip current, back flows/cross-shore flows) dan gelombang pantai tersebut sebagai sumber energi baru terbarukan. Kajian eksperimental ini dilakukan adalah untuk membuktikan bahwa dua tipe turbin yang berbeda untuk dapat mengkonversi energi arus dan gelombang bersamaan. Hasil dari kajian eksperimental adalah Wells rotor yang terpasang horisontal hanya mampu menerima energi gelombang akibat adanya gerakan orbital dari partikel-partikel air dan tidak efektif dalam menerima energi arus air karena sejajar dengan arah aliran partikel air. Bilah turbin darrieus akan menjadi resistance disaat terkena gelombang. Turbin kombinasi mempunyai self starting yang rendah dimana pada kecepatan arus 0,2 m/s dan tinggi gelombang 0,08 m. efisiensi maksimal yang diperoleh dari turbin kombinasi wells dan darrieus adalah sebesar 21,6 persen dan pada wells rotor sebesar 20,8 persen dengan ketinggian gelombang 0,123 m. Tip speed ratio (TSR) pada turbin kombinasi sebesar 1,84 dan pada wells rotor sebesar 2,26
Kajian Eksperimental Konversi Energi Gelombang Dengan Menggunakan Kombinasi Wells Rotor Dan Turbin Darrieus
Full text linkPada daerah pantai (nearshore) gelombang datang menuju pantai mempunyai massa air dan momentum, searah dengan penjalarannya. Yang mana akan menyebabkan terjadinya arus sekitar pantai, yaitu arus sepanjang pantai, arus seret dan arus balik. Hal itu bisa dimanfaatkan sebagai sumber energi baru untuk menggerakan turbin, dimana turbin tersebut harus mampu menyerap kedua energi (energi gelombang dan arus). Jika kedua jenis turbin ini digabungkan dalam satu poros, bagaimana performa turbin kombinasi tersebut dalam mengkonversi energi gelombang. Studi eksperimental ini meliputi perencanaan desain model, pembuatan model dan pengujian model yang dilakukan di kolam uji dengan gelombang buatan. Adapun spesifikasi model wells rotor adalah bentuk aerofoil NACA 0021, diameter rotor 910 mm, panjang chord 83 mm, jumlah bilah turbin 6 buah, dengan solidity 0,62. Sedangkan spesifikasi model turbin darrieus dengan bentuk aerofoil NACA 0021, diameter rotor 830 mm, panjang chord 83 mm dan jumlah bilah turbin 3 buah. Pengujian dilakukan di kolam uji dengan gelombang buatan yang divariasikan tinggi gelombang 8 cm, 10 cm, 12 cm, 14 cm, 16 cm dan 18 cm dengan periode gelombang bervariasi juga yaitu, 1 s, 1,5 s dan 2 s. Dengan variasi tersebut diharapkan dapat diketahui periode gelombang yang optimum untuk mendapatkan putaran turbin yang maksimal.
Kesimpulan dari uji eksperimental ini bahwa periode gelombang optimum yang sesuai dengan spesifikasi turbin kombinasi ini adalah sebesar 1,5 s. Wells rotor mempunyai putaran yang lebih tinggi daripada turbin kombinasi, hal itu dikarenakan blade trubin darrieus menjadi sebuah resistan, sedangkan pada turbin darrieus tidak dapat menerima energi gelombang. Turbin kombinasi antara wells dan darrieus mempunyai self starting yang rendah dimana mampu berputar pada kecepatan arus 0,2 m/s dan tinggi gelombang 0,08 m, efisiensi maksimal yang diperoleh dari turbin kombinasi wells dan darrieus adalah sebesar 21,6% dan pada wells rotor sebesar 20,8% dengan ketinggian gelombang 0,123 m dan tip speed ratio (TSR) pada turbin kombinasi wells rotor dan darrieus sebesar 1,84 dan pada wells rotor sebesar 2,26. ========== In nearshore zone the waves coming towards the shore has a water mass and momentum, the direction of the wave. It will lead to flow around the beach, among other longshore current, rip current and backflow. It can be used as a new energy source to drive the turbines, which the turbines should be able to convert the both energy sources. If both types are combined in a single turbine shaft, turbine how the performance of such combinations in converting wave energy.
In experimental studies are design modeling, and model testing performed in the test pool with artificial waves. The specifications of the model rotor wells are foil type NACA 0021 aerofoil shape, a rotor diameter of 910 mm, 180 mm chord length, the number of turbine blades 6 pieces, with the solidity of 0,62. Darrieus turbine with foil type NACA 0021 aerofoil shape, a rotor diameter of 1004 mm, 83 mm chord length and the number of turbine blades 3 pieces. Tests conducted in a tank with wave generate, wave height 8 cm, 10 cm, 12 cm, 14 cm, 16 cm and 18 cm , the wave period 1 s, 1.5 s and 2 s. These variations is expected to be known to the optimum wave periods to obtain maximum turbine rotation.
The conclusion of this experimental test that the optimum wave period in accordance with the specifications of this combination turbine is of 1.5 s. Wells rotor has a higher rotation than the turbine combination, it is because blade Darrieus Trubin be a resistance, where the Darrieus turbine can not receive the wave energy. Combination Turbine have a low self starting which is capable of runing at the current speed of 0.2 m / s and the wave height of 0.08 m, the maximum efficiency combination turbine was 21.6% and in wells rotor of 20.8% with a wave height of 0.123 m and a tip speed ratio (TSR) of the combination turbine 1.84 and the wells rotor 2.26
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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