Judul: Variabilitas Kesuburan Perairan dan Hubungannya Dengan Kondisi Oseanografi di Selat Lombok.
Abstrak: This study tried to understand the relationship between the variability of marine productivity and oceanographic condition in the Lombok Strait. We utilized Sea Surface Temperature (SST) and Chlorophyll-a data during July 2002 – December 2009 taken from remote sensing satellite of Aqua MODIS NASA, wind data during January 2002 – December 2009 from IFREMER Cersat, and Nutrient data during January 2002 – December 2005 from NOAA and WOD-NODC. The study areas divided by 4 (four) locations representing Flores sea (station 1), Northern part of Lombok strait (Station 2), Southern part of Lombok Strait (Station 3), and Indian Ocean side (Station 4). The result study showed spatial distribution of SST are about 26 – 31 oC and Chlorophyll-a are about 0.1 – 0.95 mg/m³. The temporal distribution of SST showed that during west monsoon have a warm temperature then during east monsoon the water have a cold temperature and also the temporal distribution of Chlorophyll-a have a high concentration during east monsoon and low concentration during west monsoon.We carried out the Empirical Orthogonal Function (EOF) and wavelet spectrum analysis to account for the main modes of the variability. The total variance of EOF mode 1 and 2 of SST explains 78 % for mode 1 and 8,4 % for mode 2 while Chlorophyll-a explains 32,4 % for mode 1 and 20,4 % for mode 2 of total variance. Spatial distribution at station 1 show sea surface temperature and chlorophyll is strongly influenced phenomenon semiannual influences, station 4 is influenced by the dominant influence of the phenomenon annual, while station 2 and 3 tend to be influenced phenomenon mixture of annual and semiannual. While the temporal distribution of show on the East season chlorophyll concentration tend to be hingh in the waters south of the Lombok Straits and West season chlorophyll relatively small concentrations, but relatively high chlorophyll concentrations appear only near the southeast coast island of Bali and western Lombok island. The index of marine productivity in this study has been established and found that at station 4 have high productivity rather then the others station occurred during months of June – September (dry season).
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Judul: Variabilitas massa air pada lapisan termoklin perairan Selat Lombok dan Ombai periode Januari 2004-Juni 2005
Abstrak: Arus Lintas Indonesia (ARLINDO) memiliki peranan penting dalam perubahan kondisi iklim dan dinamika lautan dunia pada umumnya dan Indonesia pada khususnya. ARLINDO sendiri masuk ke Indonesia melalui lapisan termoklin. Tujuan dari penelitian ini adalah untuk mengidentifikasi variabilitas massa air di lapisan termoklin Selat Lombok dan Ombai dengan menganalisis perubahan suhu dan salinitas yang diperoleh dari data hasil rekaman sensor Temperature, Salinity, Pressure (TSP) pada Vector Majoring Current Meter (VMCM) yang terpasang pada mooring buoy di Selat Lombok dan Ombai periode Januari 2004-Juni 2005. Data yang digunakan adalah data suhu dan tekanan dari program INSTANT (International Nusantara Stratification and Transport). Penelitian ini dilakukan pada kedalaman termoklin dan data berada pada kedalaman 200 m, 300 m, 400 m dan 500 m di Selat Lombok dan kedalaman 300 m dan 400 m di Selat Ombai. Pengolahan data menggunakan bahasa pemograman Matlab ver 7.0.1 dentifikasi massa air dilakukan dengan menggunakan metode diagram TS dari data mooring dan data CTD (Conductivity, Temperature, Depth). Untuk mengetahui periode variabilitas suhu dan salinitas dilakukan analisis deret waktu dengan mencari spektrum densitas energi dengan merubah data dari ranah waktu ke ranah frekuensi menggunakan metode Fast Fourier Transform (FFT). Hubungan antara Selat Ombai dan Lombok baik itu suhu maupun salinitas dicari dengan korelasi silang dan uji koherensi. Pola fluktusi suhu di Selat Lombok berkisar antara 1,31-3,13 °C dan rata-rata yang berkisar 10,67-14,05 °C. Spektrum suhu yang dominan di Selat Lombok adalah sinyal 7,8-8,7 bulan yang kemungkinan dipengaruhi oleh instability barotropik gyres di Samudera Hindia. Pola fluktuasi salinitas berkisar antara 0,02- 0,13 dan rata-ratanya berkisar antara 34,77-34,91. Sinyal spektrum salinitas yang dominan adalah sinyal pasang surut 2 mingguan. Pola fluktuasi Suhu di Selat Ombai berkisar antara 1,80-2,27 °C dan rata-rata berkisar antara 10,54-13,52 °C. Spektrum suhu yang mendominasi sekitar enam bulanan yang merupakan sinyal tengah musiman (seasonal). Pola fluktuasi salinitas sebesar 0,08 dengan rata-rata berkisar 34,80-34,87. Sinyal spektrum pada salinitas yang mendominasi adalah sinyal pasang surut dua mingguan. Musim timur (Juni-Juli-Agustus) baik di Selat Lombok dan Ombai terjadi kecenderungan penurunan suhu. Penurunan ini diduga terjadi karena adanya pengaruh dari ARLINDO yang besar sehinggga dapat menurunkan suhu. Massa air ARLINDO diindikasikan masih ada di perairan Selat Lombok dan Ombai dengan ditemukannya massa air Northern Subtropical Lower Water (NSLW) dan massa air Northern Pacific Intermediate Water (NPIW). Hasil korelasi silang dan koherensi menunjukkan bahwa suhu lebih berpengaruh daripada salinitas dalam perubahan massa air lapisan termoklin di Selat Lombok dan Ombai.
Keyword: Salinitas, Massa air, Kondisi umum oseanografi perairan Indonesia timur

Judul: Sintesis Paduan Ti-6Al-4Nb sebagai Matrial Implan Pengganti Komponen Tibial
Abstrak: Synthesis of Ti-6Al-4Nb alloy was done by melting using Tri Arc Melting Furnace. Each sample was remelted five times to ensure the homogenity. Aluminum and niobium addition were expected to stabilize α phase and β phase until the αβ-titanium alloy was resulted. Yet based on the experiment, it was α-titanium alloy resulted. α-titanium alloy was a Hexagonal Close Packed (HCP) crystalline structure which would be cracked if deformation non-uniaxial happens. The presence of oxygen in pure titanium significantly increased the hardness of titanium. The addition of aluminum was also able to increase the hardness of titanium alloy because aluminum more stabilize the α phase in the α-titanium alloy. The corrosion ressistance of titanium could be increased by adding aluminum and niobium. Titanium coating with HA/chitosan composite was also proved in decreasing the corrosion rate because it barried direct interaction between titanium alloy and corrotion solution.
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