Judul: Karakteristik Briket Arang dari Tempurung Kelapa (Cocos nucifera.) dan Kayu Ulin (Eusideroxylon zwageri.).
Abstrak: Penelitian ini bertujuan untuk mengetahui karakteristik briket arang tempurung kelapa (Cocos nucifera) dan kayu ulin (Eusideroxylon zwageri) yang berupa sifat fisis dan mekanis. Briket arang dibuat dengan cara konvensional dengan penambahan perekat kanji dan molasses beserta komposisi arang tempurung kelapa (Cocos nucifera) dan kayu ulin (Eusideroxylon zwageri) yang berbeda setiap jenisnya, mulai dari komposisi 100% sampai 50%-50%. Hasil penelitian menunjukkan sifat fisis dan sifat mekanis briket arang sebagai berikut, kerapatan 0.71-1.07 g/cm³, keteguhan tekan 1.64-55.60 kgf/cm², kadar air 3.62% - 7.99%, kadar zat menguap 14.15-28.98%, kadar abu 0.53% -3.02%, nilai karbon terikat 63.05% -77.92%, dan nilai kalor 6141.77-7374.60cal/g.
Keyword: batok kelapa, kayu ulin, briket arang, tapioka, molasses

Judul: Karakteristik Briket Arang Tandan Kelapa Sawit dengan Perekat Tapioka
Abstrak: Arang yang diambil dari pabrik PTP Nusantara 7 Bekri Lampung disaring dengan saringan 100 mesh dan dikeringkan pada suhu 60oC selama 24 jam. Dengan mencampurkan perekat tapioka dengan variasi kadar 4%, 6%, dan 8% pada arang tandan kelapa sawit dapat dibuat briket arang. Bahan baku dikempa dengan hidrolik manual dan dikeringkan di dalam oven pada suhu 90oC selama 24 jam. Briket yang dihasilkan memiliki sifat fisik kadar air sebesar 4.76%, 5.15%, dan 5.87%. Kadar abu sebesar 20.70%, 21.41%, dan 21.87%. Kadar zat terbang sebesar 21.93%, 22.17%, dan 22.27%. Kadar karbon terikat sebesar 51.21%, 50.86%, dan 50.04%. nilai rapat massa sebesar 0.45 gram/cm3, 0.47 gram/cm3, dan 0.48 gram/cm3. Nilai kalor briket arang tersebut berturut-turut 3410.50 Kal/gram, 3320.77 Kal/gram, 3141.30 Kal/gram. Penambahan perekat kanji ternyata tidak memberikan pengaruh yang begitu besar terhadap sifat fisik yang dihasilkan dan briket dengan kadar perekat 6% memiliki nilai karakter fisik yang optimal.
Keyword: briket Arang, nilai kalor dan limbah tandan kelapa sawit

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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