Judul: Penerapan Bahan Bakar Biogas pada Motor Bensin dengan Modifikasi Karburator dan Variasi Rasio Kompresi
Abstrak: Biogas is one of the gaseous bio-energy can be applied into gasoline motors with some modification of components. The objectives of this research are applying the biogas fuel in gasoline engine with carburetor modification, measuring and getting value of maximum power and maximum torque and minimum value of the specific fuel consumption of each variation of compression ratio. The results of research were the biogas fuel on gasoline motors could be implemented directly, carburetor modifications changed the ratio of air and fuel ratio of 14.7: 1 (gasoline) to 5.7:1 (biogas) as of gasoline engine could be operated with engine speed over 1500 rpm up to 4500 rpm in a stable condition. The maximal power values for each compression ratio were 0.827 kW at compression ratio (CR 7.6), 0.953 kW (CR 8.3), 0.838 kW (CR 9.0) and 0.764 kW (CR 10.0). Maximum torque values were 3.071 N.m at compression ratio (CR 7.6), 4.274 N.m (CR 8.3), 3.598 N.m (CR 9.0), and 4.074 N.m (CR 10.0). The results of lowest value of specific fuel consumption were 4.29 m3/kWh at compression ratio (CR 7.6), 2:13 m3/kWh (CR 8.3), 1.84 m3/kWh (CR 9.0), and 2.92 m3/kWh (CR 10.0). The optimal of compression ratio was 8.3.
Keyword: 

Judul: Rekayasa Pengaturan Udara Berdasarkan Perubahan Kandungan Metana pada Biogas Umpan ke Motor Bakar Bensin
Abstrak: Pembakaran metana dengan jumlah udara yang tidak sesuai mengakibatkan konversi energi kimia ke mekanik pada motor bakar tidak optimum. Sementara itu, kandungan metana di dalam biogas umumnya beragam sehingga diperlukan rekayasa pengaturan udara agar pembakaran menjadi sempurna. Hasil pengukuran kinerja motor bakar dengan perlakuan yang dilakukan menunjukkan daya tertinggi 4.086 kW terjadi pada biogas dengan kandungan metana 92 % di putaran 3000 rpm dan nilai daya terendah adalah 3.236 kW pada biogas dengan kandungan metana 57 % di putaran 3000 rpm. Penggunaan bahan bakar paling hemat terjadi pada kandungan metana 92 % sedangkan penggunaan bahan bakar yang boros terjadi pada kandungan metana 57 %. Berdasarkan perhitungan stoikiometri kandungan 57 %, 62 %, 77%, 82% dan 92 % berturut-turut memiliki air fuel ratio 1: 13.54, 1: 13.97, 1: 15.26, 1: 15.69, 1: 16.55. Efisiensi termal paling tinggi terdapat pada power maksimum pada masing masing bahan bakar, nilai dari efisiensi termal mendekati efisiensi termal dari motor bakar bensin yaitu 25 %.
Keyword: biogas, amda, metana, motor bakar, power

Judul: The Fern of West Timor  East Nusa Tenggara
Abstrak: Based on this study there are 58 species belonging to 36 genera. They are Achrosticum (1 species), Adiantum (5 species), Amphineuron (3 species), Asplenium (4 species), Athyrium (1 species), Belvisia (1 species), Botrycium (1 species), Ceratopteris (1 species), Christella (4 species), Ctenitis (1 species), Ctenopteris (1 species), Cyathea (1 species), Davallia (2 species), Dennstaedtia (1 species), Diplazium (2 species), Doryopteris (1 species), Drynaria (2 species), Dryopteris (1 species), Gleichenia (1 species), Heterogoniurn (1 species), Humata (1 species), Lycopodium (1 species), Microlepia (1 species), Microsorium (1 species), Nehprolepis (2 species), Oleandra (1 species), Platycerium (1 species), Pleocnemia (1 species), Pteris (5 species), Pyrrosia (1 species), Sellaginela (1 species), Selliguea (1 species), Sphaerostephanos (2 species), Tectaria (1 species), Trichomanes (1 species), and Vittaria (1 species).
Keyword: