Judul: Rancang bangun alat pengering dengan memanfaatkan panas kondensor AC ruangan (kasus pengeringan chips kentang
Abstrak: Drying process is a method to decrease moisture content of the food products. The objectives of the research were to design and evaluate the performance of drying chamber using rejected heat of AC condenser for potatoes chips drying, determine potatoes moisture content and drying efficiency, and to investigate the influence of condenser fan velocity on cooling capacity. The drying chamber had 50.2 × 50.2 × 150.2 cm volume dimension, which contained seven aluminium trays. The chamber was connected to the condensing unit of an air conditioner. Potatoes were peeled, and cut sliced into 2.5 mm thickness of slices and then blanced using hot water. Then the slices were dried by using drying chambers for 6 h at high velocity fan, low velocity fan and substitution fan. The result showed that rejected heat of a room AC could be used for potatoes chips drying with temperature ranged from 33.88 to 44.05oC. The drying process with substitution fan was combined with reverse tray treatment produced relatively uniform moisture content of dried chips (8.20 ± 1.04% wb). The drying process resulted 20.42 – 23.32% of drying efficiency to AC condenser heat and 67.17 – 78.77% to AC electric energy consumtion. The velocity of condenser fan did not significantly influence on the cooling capacity. It can be concluded that the drying chamber using rejected heat of AC condenser can be used for the drying of agricultural products e.g. the potatoes drying.
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Judul: Rancang bangun dan Uji Kinerja Pengering  Singkong Efek Rumah Kaca (ERK)-Hibrid Tipe Rak dengan Turbin Ventilator untuk Sirkulasi Udara
Abstrak: Cassava is the fourth leading commodity after rice, wheat and corn. Market demand and high productivity of cassava make it as one of the potential export commodities. In case for export or industrial use fresh cassava must be processed first into semi-finished materials for added value. It will be better if the added value is left to the farmer. For the purpose, the farmer needs to be furnished with proper and affordable technology. This study aims to design, construct and testing a dryer which apply the principle of greenhouse effect by additional heating of biomass furnace. Dryer is designed with a capacity of 180 kilograms cassava from 65% wb moisture content up to 13% wb moisture content. Drying chamber has dimensions of 2 m x 1.5 m x 2.4 m (L x W x H) with 30 shelves. This dryer has a cross flow type heat exchanger and regulating the circulation of air using a turbine ventilator. On testing with the full capacity, the dryer can dried up 180 kg cassava chips from 61.31 %wb (158.53 %db) moisture content to 9.87 %wb (11.01 %db) moisture content. On these test the dryer has a total efficiency of 18.3%, energy share of solar energy 7.72% and biomass 92.28%, drying time is 49 hours at a rate of 4.50 %db/h. While testing with half capacity, was dried 95 kg cassava chips from moisture content of 69.47%wb (232.26 %db) to 8.81 %wb (9.67 %db), the total efficiency of the dryer was 14.84% with the share of energy from solar energy 7.31% and 92.69% of the biomass, drying time required is 28 hours with the drying rate 8.56 %db/h.
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Judul: Persamaan Geodesik Black Hole dengan Metrik Kerr 4+1 Dimensi dalam Koordinat Waktu Kosmik
Abstrak: Persamaan geodesik black hole dengan metrik Kerr 4+1 dimensi dalam koordinat waktu kosmik merupakan interpretasi lain dari persamaan geodesik black hole dengan metrik Kerr 4+1 dimensi, dimana acuan waktu yang digunakan diubah dari koordinat waktu wajar (proper time) ke dalam koordinat waktu kosmik (cosmic time). Waktu kosmik merupakan koordinat waktu yang dimana pengamat bergerak mengikuti ekspansi dari alam semesta. Penelitian ini merekonstruksi persamaan geodesik black hole dengan metrik Kerr 4+1 dimensi yang telah ditemukan pada penelitian sebelumnya menjadi persamaan geodesik yang memiliki fungsi terhadap dimensi waktu (t). Hasil akhir dari transformasi persamaan dapat digunakan sebagai bahan studi pustaka untuk penelitian lebih lanjut mengenai persamaan geodesik black hole dalam koordinat waktu kosmik.
Keyword: Dimensi ekstra, Metrik Kerr, Persamaan geodesik, Waktu kosmik