Judul: Karakteristik Wood Pellet Campuran Cangkang Sawit dan Kayu Bakau (Rhizhophora spp.)
Abstrak: Wood pellet adalah bahan bakar padat berbentuk silinder yang dapat menjadi alternatif energi. Penelitian ini bertujuan untuk menguji karakteristik wood pellet cangkang sawit dan kayu bakau. Kosentrasi serbuk cangkang sawit dan kayu bakau (100%:0%, 75%:25%, 50%:50%, 25%:75%, 0%:100%) dikempa pada wood pellet hidrolik dengan suhu 200°C selama 15 menit. Hasil penelitian menunjukkan bahwa, penambahan setiap 25% kayu bakau terhadap cangkang sawit meningkatkan nilai kadar air, kerapatan, keteguhan tekan, zat terbang tetapi dapat menurunkan nilai karbon terikat, kadar abu dan nilai kalor. Karakteristik wood pellet seperti kerapatan, keteguhan tekan, kadar air, zat terbang, kadar abu, karbon terikat dan nilai kalor secara berturut-turut memiliki nilai 1.1204-1.1564 g/cm3, 32–700 kgf/cm2, 4.35-5.78%, 72.44-74.70%, 1.09-1.36%, 18.43-21.85%, 4448-4859 kal/g.
Keyword: wood pellet, kayu bakau, cangkang sawit

Judul: Karakteristik Biopelet Campuran Cangkang dan Pelepah Kelapa Sawit (Elaeis guineensis Jacq.)
Abstrak: Biopelet adalah salah satu energi alternatif terbarukan yang memiliki keseragaman ukuran, bentuk, densitas, dan kandungan energi. Tujuan penelitian ini adalah menguji karakteristik biopelet campuran cangkang dan pelepah kelapa sawit, serta menentukan komposisi bahan baku yang dapat menghasilkan biopelet dengan kualitas terbaik. Bahan baku yang digunakan adalah campuran cangkang dan pelepah sawit dengan persentase campuran 100%:0%, 75%:25%, 50%:50%, 25%:75%, dan 0%:100%. Pembuatan biopelet menggunakan serbuk 80 mesh dengan tekanan 526.4 kg/cm2 pada suhu 200oC selama 15 menit. Jenis pengujian yang dilakukan terhadap biopelet meliputi kerapatan, keteguhan tekan, kadar air, zat terbang, kadar abu, karbon terikat, dan nilai kalor. Hasil pengujian menunjukkan kerapatan 1.02-1.28 g/cm3, keteguhan tekan 23.73-216.31 kgf/cm2, kadar air 2.87-4.65%, zat terbang 67.24-72.99%, kadar abu 4.48-7.73%, karbon terikat 17.49-22.16%, dan nilai kalor 3977-4666 kal/g. Biopelet yang mempunyai kualitas terbaik terdapat pada campuran cangkang dan pelepah sawit sebesar 75%:25%.
Keyword: biopelet, cangkang sawit, pelepah sawit, nilai kalor

Judul: A Continuous Vaccination Strategy in the SVIR Epidemic Model
Abstrak: Vaccination is conducted to minimize the spread of a disease. The vaccination is usually done several times within a fixed time interval. In the SVIR model, it is assumed that individuals do not get immediate immunity following a vaccination program. So according to process of vaccination on SVIR model, there are two strategies, i.e. the continuous vaccination strategy (CVS) and the pulse vaccination strategy (PVS). In this study, only the CVS strategy in epidemic model SVIR is considered. Results of the study indicate that dynamics of the CVS system depends on the basic reproductive number. If the basic reproductive number is less than one, then the disease-free fixed point is asymptotically stable. It means that the disease will eventually disappear from the population. Conversely, if the basic reproductive number is greater than one, then the endemic fixed point is asymptotically stable, which means that the disease will remain exist in the population. Simulation result shows that the vaccination would minimize the spread of disease by reducing the basic reproductive number. If the time for the vaccinated recipients to obtain the immunity, as well as a possibility of vaccinated recipients to be infected are neglected, then the disease will be eradicated. This condition is called an over-evaluating effect of vaccination.
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