Judul: Status Kesuburan Perairan Waduk Jatigede, Sumedang, Jawa Barat
Abstrak: Waduk Jatigede dibangun di atas wilayah seluas lima kecamatan. Aktivitas masyarakat di sekitar waduk dapat memberikan masukan bahan organik dan organik yang menyebabkan perubahan tingkat kesuburan perairan. Kesuburan perairan merupakan kemampuan tingkat produksi suatu perairan. Status kesuburan perairan umumnya dibagi menjadi tiga tingkatan, yaitu oligotrofik, mesotrofik, dan eutrofik. Penelitian ini bertujuan untuk menentukan tingkat kesuburan perairan Waduk Jatigede, Sumedang, Jawa Barat dengan beberapa pendekatan. Penelitian dilakukan pada bulan Februari sampai April 2021 yang diambil pada tujuh titik pengamatan. Status kesuburan perairan dianalisis menggunakan indeks Nygaard, indeks Thunmark, dan TSI. Hasil penelitian menunjukkan bahwa komposisi kelimpahan fitoplankton di perairan Waduk Jatigede didominasi oleh Cyanophyceae yang mengindikasikan perairan eutrofik. Status kesuburan perairan Waduk Jatigede berdasarkan indeks Nygaard, indeks Thunmark, dan TSI tergolong ke dalam perairan eutrofik., Jatigede Reservoir was built on an area of five sub-districts. Community activities around the reservoir can provide input organic and inorganik materials that causes changes in the level of trophic states. Trophic state is the ability of the production level of a waters. Trophic state is generally divided into three levels, namely oligotrophic, mesotrophic, and eutrophic. This study aims to determine the level of trophic state of Jatigede Reservoir, Sumedang, West Java with several approach. The study was conducted in February to April 2021 which was taken at seven observation points. Trophic state was analyzed using Nygaard index, Thunmark index, and TSI. The results showed that the composition of the abundance of phytoplankton in the waters of Jatigede Reservoir was dominated by the Cyanophyceae which indicated eutrophic waters. The trophic state of Jatigede Reservoir based on Nygaard index, Thunmark index, and TSI is classified as eutrophic waters.
Keyword: eutrophic, phytoplankton, reservoir, trophic state, water quality

Judul: Spatial Distribution of Nitrogen in the Waters of Jatigede Reservoir, Sumedang, West Java
Abstrak: Materi yang masuk ke dalam perairan dapat berupa bahan organik dan anorganik yang bermuatan nitrogen. Sumber masukan nitrogen yang beragam dapat memengaruhi pola penyebaran nitrogen di Waduk. Penelitian ini bertujuan untuk menganalisis distribusi nitrogen secara spasial di perairan Waduk Jatigede, Sumedang, Jawa Barat. Penelitian dilaksanakan pada bulan Februari-April 2021. Analisis data yang digunakan berupa uji signifikansi antara lapisan dan antarawaktu, penentuan musim, kesamaan karakteristik stasiun berdasarkan kualitas air, pemetaan sebaran spasial nitrogen, dan analisis korelasi nitrogen dengan parameter kualitas air. Waduk Jatigede terdiri dari tiga zona, yaitu Zona Riverin, transisi, dan lakustrin. Konsentrasi nitrat, nitrit, dan nitrogen total tinggi di Zona Riverin pada lapisan epilimnion dan di Zona Transisi pada lapisan hipolimnion. Konsentrasi amonia tertinggi di Zona Lakustrin pada lapisan epilimnion dan hipolimnion. Terdapat hubungan antaraa nitrogen dengan parameter kualitas air seperti COD, kekeruhan, TSS, dan DO. Konsentrasi tertinggi nitrogen terjadi pada lapisan hipolimnion. Nitrogen tersebar dengan konsentrasi bervariasi secara vertikal dan cenderung seragam secara horizontal. Nitrogen memiliki tingkat konsentrasi dengan kecenderungan lebih tinggi di Zona Riverin secara horizontal dan di lapisan hipolimnion secara vertikal. Secara spasial, tingkat konsentrasi nitrogen dipengaruhi oleh COD, kekeruhan, TSS, dan DO di perairan., Materials enter waters can be form of organic and inorganic containing nitrogen. Various sources of nitrogen input which can affect nitrogen distribution pattern. This study aims to analyze the nitrogen spatial distribution in Jatigede Reservoir, Sumedang, West Java. Research carried out in February-April 2021. Analysis of data used are test of significance between layers and over time, season determination, similarity of station characteristics based on water quality, mapping of nitrogen spatial distribution, and nitrogen correlation analysis with water quality parameters. Jatigede Reservoir consists of three zones, namely riverine, transition, and lacustrine zones. Concentrations of nitrate, nitrite, and total nitrogen were high in riverine in epilimnion and in transition in hypolimnion. The highest amonia concentration was in lacustrine in epilimnion and hypolimnion. There is relationship between nitrogen and water quality parameters such as COD, turbidity, TSS, and DO. The highest nitrogen concentration occurs in hypolimnion. Nitrogen is dispered with varying concentrations vertically and tends to be uniform horizontally. Nitrogen has a concentration tend to be higher in riverine horizontally and in hypolymnion vertically. Spatially, nitrogen concentration is influenced by COD, turbidity, TSS, and DO in waters.
Keyword: distribution, Jatigede Reservoir, nitrogen

Judul: The Exploration of Discrete Logarithm over Finite Field GF(3m)
Abstrak: The security of many public~key algorithms is based on the problem of finding discrete logarithms. The generalized discrete logarithm problem is the following: given a finite cyclic group G of order n, a generator a of G, and an element fl E G, find the integer x, 0 ~ x ~ n - 1, such that 0: = fl. Algorithm for discrete logarithm problem focused on Menezes et al. (1997) that consist of exhaustive search algorithm, the baby-step giant-step algorithm, Pollard's rho algorithm, Pohlig-Hellman algorithm, and index-calculus algorithm. These algorithms are explorated to be used in discrete logarithm problem over finite field GF(3m ). The exploration also produces some algorithms, i.e. naif negative algorithm, baby-step mother-step algorithm, baby-step mother free-step algorithm, and baby-step free-step algorithm. All algorithms implemented using Maple 11. The Pohlig-Hellman and baby-step giant-step algorithms are efficient enough to be used in discrete logarithm problem over finite field GF(3m ) for m < 20.
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