Judul: Vertical Distribution Of Temperature And Dissolved Oxygen Related To Floating Cage Activitiy In Cirata Reservoir, West Java
Abstrak: Cirata Reservoir was built for hydropower to supply electricity for Java and Bali Islands. It is also used for fish culture in floating cage. However, aquaculture in Cirata Reservoir has been far exceeded carriying capacity. This research aims to analyze the vertical dissolved oxygen (DO) profile, determining the factors causing the hypoxia, and qualitatively explaining the response of hypoxia related to floating cage activity. Investigation and water sampling were conducted at four sites with and without floating cage activity. Data on DO, temperature, pH and chemical oxygen demand (COD) were collected weekly for six weeks from April to May 2015. The DO concentration in intensive cage area was lower than in no cage area. DO concentration in areas with intensive cage fell to hypoxia (< 3 mg/l) at 7 m of depth in the first week and moved upward to 4 m of depth in sixth week observation. COD and pH in intensive cage areas were significantly different (P<0.05) from the area with no cage activitiy. The hypoxic and anoxic layers could be dangerous if it continues to be supported by the long rainy days because it may be followed by the upwelling events and the massive fish kills. Nitrate, nitrite and ammonium in intensive cage area have no significantly diffenrent concentration from no cage area. But generally, these parameters have higher concentration in intensive cage area. The highest nitrite concentration found in water column at 20 m (0.003 mg/l). Orthophosphate and chlorophyll-a concentration in intensive cage area is significantly higher than no cage area. Vertically, orthophosphate and chlorophyll-a also have significantly different concentration. From dendrogram graph it is showed that floating cage activities affect to the different characteristic of N, P and chlorophyll-a in Cirata Reservoir.
Keyword: chlorophyll-a, Cirata Reservoir, floating cage, hypoxia, oxygen stratification

Judul: The Vertical Profile of Dissolved Oxygen in Jatigede Reservoir, Sumedang, West Java
Abstrak: Waduk merupakan perairan yang relatif tenang dan dalam. Konsentrasi DO pada waduk umumnya akan mengalami penurunan seiring dengan bertambahnya kedalaman. Penelitian ini bertujuan menganalisis profil kandungan oksigen terlarut secara vertikal dan kaitannya dengan profil fisika-kimia secara vertikal di perairan Waduk Jatigede, Sumedang, Jawa Barat. Pengamatan dilaksanakan pada titik pengamatan yang mewakili Zona Riverin, Zona Transisi, dan Zona Lakustrin. Parameter kualitas air yang diamati meliputi DO, suhu, DHL, COD, kekeruhan, pH, kecerahan, dan kecepatan arus. Hasil pengukuran DO berkisar antara 0,3-8,3 mg L-1 yang menurun seiring dengan bertambahnya kedalaman. Suhu berkisar antara 25,9-32,4 ̊C. DHL berkisar antara 158,8-219 μS cm-1. COD berkisar antara 20,76-44,63 mg L-1. Kekeruhan berkisar antara 1,16-183 NTU. pH berkisar antara 7,68-10,93. Kecerahan berkisar antara 84- 138 cm. Kecepatan arus berkisar antara kurang dari 0,1 hingga 0,15 m s-1. Parameter fisika-kimia yang memengaruhi DO memiliki korelasi yang berbeda-beda dan keberadannya sangat fluktuatif. Kesimpulan dari penelitian ini adalah distribusi vertikal DO di Waduk Jatigede tergolong ke dalam tipe distribusi clinograde. Profil vertikal DO memiliki korelasi dengan parameter fisika-kimia perairan, terutama suhu, DHL, COD, kekeruhan, dan pH., Reservoirs are relatively calm and deep waters. The concentration of DO in the reservoir will generally decrease with the increasing depth. This study aims to analyze the profile of dissolved oxygen content vertically and its relation to the vertical physical-chemical profile in the waters of Jatigede Reservoir, Sumedang, West Java. Observations were carried out at observation points representing the Riverine Zone, Transition Zone, and Lacustrine Zone. The water quality parameters observed included DO, temperature, conductivity, COD, turbidity, pH, water transparency, and current velocity. DO measurement results ranged from 0,3-8,3 mg L-1 which decreased with increasing depth. The temperature ranged from 25,9 to 32,4 ̊ C. Conductivity ranged from 158,8 to 219 μS cm-1. COD ranged from 20,76 to 44,63 mg L-1. Turbidity ranged from 1,16 to 183 NTU. pH ranged from 7,68-10,93. Water transparency ranged from 84-138 cm. Current velocity ranged from less than 0,1 to 0,15 m s-1. The physicalchemical parameters that affect DO have different correlations and their existence is highly volatile. The conclusion of this study is the vertical distribution of DO in Jatigede Reservoir belongs to the distribution type clinograde. DO vertical profile correlates with water physical-chemical parameters, especially temperature, conductivity, COD, turbidity, and pH.
Keyword: clinograde, correlation, dissolved oxygen, Jatigede Reservoir

Judul: Konstruksi aritmetika kurva eliptik F(2m) supersingular dan non-supersingular untuk skema kunci publik ElGamal
Abstrak: Algoritme ElGamal adalah salah satu algoritme kunci publik dengan aritmetik modular p yang mempunyai struktur grip siklik Z(p). Tingkat keanaman algoritme ini terletak pada pemecahan masalah logaritme diskret dari Z(p). Akan tetapi, tingkat keamanan tadi tahun ke tahun semakin menurun yang disebabkan kemampuan pemecahan algoritme diskret semakin meningkat. Untuk memenuhi tingkat keamanan yang memadai dibutuhkan p yang cukup besar yang menyebabkan proses enkripsi dan dekripsi menjadi lambat.
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