Analisa Perancangan Turbin Darrieus Pada Hydrofoil NACA 0015 Dari Karakteristik CL dan CD Pada Variasi Sudut Serang 0˚ Sampai 360˚

Seiring dengan meningkatnya kebutuhan akan energi listrik serta menipisnya cadangan bahan bakar fosil, maka keadaan tersebut memaksa manusia untuk mencari energi alternatif (renewable energy) yang dapat diperbaharui yang dapat menggantikan bahan bakar fosil. Banyak energi alternatif yang dapat diperbaharui seperti pembangkit listrik tenaga air yang menjadi sumber energi yang berpotensi besar untuk dikembangkan saat ini. Terlebih dalam hal ini geografis Indonesia 63% wilayahnya terdiri dari laut menyimpan banyak potensi energi alternatif, khususnya energi arus laut. Maka dari itu perlu dikembangkan suatu alat yang dapat mengubah potensi energi arus air menjadi energi listrik sehingga cocok digunakan untuk perairan Indonesia. Dalam tugas ahir ini dilakukan perhitungan nilai torsi, daya turbin, daya hidrolis, dan efisiensi turbin pada turbin Darrieus 3 sudu dengan menggunakan karakteristik hydrofoil NACA 0015, diameter 0.6 m, tinggi sudu 0.8 m, dan panjang chord 0.18 m dengan variasi sudut serang 0˚ sampai dengan 360˚ dengan variasi kecepatan 2 m/s, 2.5 m/s, 3 m/s, 3.5 m/s, dan 4 m/s. Dalam perhitungan ini nilai CL(Lift Coefficient) dan CD(Drag Coefficient) diperoleh dari hasil simulasi. Hasil simulasi akan menunjukkan hasil perhitungan berupa nilai torsi, daya turbin, daya hidrolis, dan efisiensi turbin. Dimana diperoleh nilai efisiensi pada kecepatan aliran 2 m/s sebesar 17.14 %, kecepatan aliran 2.5 m/s sebesar 19.776 %, kecepatan aliran air 3 m/s sebesar 21.02%, kecepatan aliran air 3.5 m/s sebesar 22.44 % dan kecepatan aliran 4 m/s sebesar 25.833 %. Dimana nilai efisiensi tertinggi didapat pada kecepatan 4 m/s sebesar 25.833 %. Kata kunci: Lift Coefficient, Drag Coefficient, Hydrofoil NACA 0015, Turbin Darrieus. vii

PENGEMBANGAN DAN ANALISA KESERAGAMAN ALIRAN TEROWONGAN ANGIN TIPE TERBUKA SEBAGAI SARANA PENGUJIAN AERODINAMIKA

Terowongan angin sebagai sarana praktikum dan riset di bidang aerodinamika sangat penting keberadaannya, namun harganya yang mahal seringkali menjadi kendala utama di berbagai institusi pendidikan. Pengembangan terowongan angin dengan biaya murah namun memenuhi syarat sangat penting untuk dilakukan. Penelitian ini bertujuan untuk mengembangkan terowongan angin tipe terbuka dan menguji keseragaman aliran pada seksi uji sehingga layak untuk dipergunakan. Terowongan angin dibuat dari plat besi dengan tebal 1,4 mm, angin dihasilkan oleh fan aksial yang digerakkan dengan motor listrik dengan daya 1 HP. Pengujian dilakukan pada bebrapa kecepatan angin yang berbeda, variasi kecepatan diperoleh dengan mengubah putaran motor listrik menggunakan inverter. Hasil pengujian menunjukkan bahwa kecepatan terendah yang dicapai adalah 2 m/s dan tertinggi 5,8 m/s. Pada kecepatan 2 m/s variasi kecepatan pada seksi uji sekitar 0,1 m/s , dan pada kecepatan 5,8 m/s sekitar 0,1 hingga 0,3 m/s Kata Kunci : terowongan angin, aerodinamika, open circuit wind tunne

The tensor renormalization group study of the general spin-S Blume-Capel model

We focus on the special situation of $D=2J$ of the general spin-S Blume-Capel model on the square lattice. Under the infinitesimal external magnetic field, the phase transition behaviors due to the thermal fluctuations are discussed by the newly developed tensor renormalization group method. For the case of the integer spin-S, the system will undergo $S$ first-order phase transitions with the successive symmetry breaking with the magnetization $M=S,S-1,...0$. For the half-integer spin-S, there are similar $S-1/2$ first order phase transition with $M=S,S-1,...1/2$ stepwise structure, in addition, there is a continuous phase transition due to the spin-flip $Z_2$ symmetry breaking. In the low temperature regions, all first-order phase transitions are accompanied by the successive disappearance of the optional spin-component pairs($s,-s$), furthermore, the critical temperature for the nth first-order phase transition is the same, independent of the value of the spin-S. In the absence of the magnetic field, the visualization parameter characterizing the intrinsic degeneracy of the different phases clearly demonstrates the phase transition process.Comment: 6 pages, 7 figure

Triplectic Gauge Fixing for N=1 Super Yang-Mills Theory

The Sp(2)-gauge fixing of N = 1 super-Yang-Mills theory is considered here. We thereby apply the triplectic scheme, where two classes of gauge-fixing bosons are introduced. The first one depends only on the gauge field, whereas the second boson depends on this gauge field and also on a pair of Majorana fermions. In this sense, we build up the BRST extended (BRST plus antiBRST) algebras for the model, for which the nilpotency relations, s^2_1=s^2_2=s_1s_2+s_2s_1=0, hold.Comment: 10 pages, no figures, latex forma

Yang-Mills vacuum structure and quantum gravity

Using renormalization group methods we calculate the derivative expansion of the effective Lagrangian for a covariantly constant gauge field in curved spacetime. Curvature affects the vacuum, in particular it could induce phase transitions between different vacua. We also consider the effect of quantum fluctuations of the metric , in the context of a renormalizable $R^2$ theory. In this case the critical curvature depends on the gravi tational coupling constants.Comment: Latex file, 8 page

A Locked City: The Japanese Company Nitchitsu’s Building of Hŭngnam

Hŭngnam City has received scholarly attention as a symbolic space in which urbanization followed industrialization during the Japanese colonial era in Korea. The Japanese company Nihon Chisso Hiryō Kabushiki Kaisha (Nitchitsu) took this secluded region and built it into a city with world-class production and urban facilities, transforming it into an enterprise city dubbed “the kingdom of Nitchitsu.” However, there is a dearth of analyses which focus on Nitchitsu’s “planning,” “constructing,” and “ruling” of Hŭngnam rather than the aspects of its brilliant “modernization.” In this regard, this article focuses on the city structure of colonial Hŭngnam and how this structure molded a “Japanese settler community.” In particular, this article examines how the families of lower-class laborers from Nitchitsu’s main Japanese factory in Minamata, through the process of moving into Hŭngnam, were formed into a “Japanese settler community” in which they were discriminated against in the colonial city. Furthermore, the article reviews Nitchitsu’s strategy for operating the city through an analysis of detailed records of the company’s donations. The Japanese approach relative to Nitchitsu and Hŭngnam, in order to stabilize the “Japanese settler community” and maximize profits and operations, sought to plan and operate the city as a space only for themselves. Hŭngnam was built in a manner that concentrated all capacity towards the “Japanese settler community” and Nitchitsu, and blocked any “urban integration” which disrupted the company’s pursuit of profit, turning Hŭngnam into a locked “fortress city” built just for Nitchitsu. In sum, this article, by offering a narrative analysis of the closed-minded manner in which Hŭngnam was made into a “fortress” closed to the rest of Korea to maximize profit margins, and shows the flawed historical development of this urban industrial complex that prefigured the Nitchitsu corporation’s role in the tragic emergence of “Minamata disease” in the region after World War II