Judul: Rancang Bangun Mesin Pemecah Kulit Buah dan Pemisah Biji Kakao
Abstrak: Langkah awal yang mempengaruhi kualitas dan biaya dalam pengolahan buah kakao yaitu pemecahan buah dan pemisahan biji. Penanganan pascapanen kakao masih menggunakan cara tradisional, seperti menggunakan parang. Altenatif lain yang dilakukan yaitu penggunaan mesin pemecah kulit buah dan pemisah biji kakao. Tujuan dari penelitian ini adalah melakukan rancang bangun dan pengujian kinerja mesin pemecah kulit buah kakao dengan modifikasi sistem pemecahan menggunakan pisau rotary dan pemisahan biji menggunakan ayakan. Rancangan mesin memiliki komponen fungsional yakni rangka dari besi siku 3 x 3 cm, bagian yang bersentuhan dengan bahan yaitu hopper, pisau rotary, rumah pemecahan, ayakan, dan hopper pengutipan biji dibuat dari besi stainless (1 mm). Mesin digerakkan oleh motor listrik 1 hp dengan 2200 rpm. Penyaluran tenaga menggunakan sabuk dan puli, gearbox, serta lengan. Kapasitas kerja pemecahan yaitu 277 kg/jam dan kapasitas kerja pemisahan yaitu 266 kg/jam dengan waktu rata-rata keseluruhan proses yaitu 110 detik (8 kg sampel). Hasil yaitu 1.2 kg/jam biji per proses dengan persentase 15%. Lainnya yaitu 65 % kulit dan plasenta, 19 % massa yang biji tidak terlepas, dan 1 % massa yang terlempar atau hilang. Efisiensi kapasitas kerja yaitu 89.6 %. Efisiensi kualitas yaitu 60 % dan kehilangan 7.6 %.
Keyword: ayakan, kakao, pemecah buah, pemisah biji, pisau rotary

Judul: Modifikasi Desain dan Uji Kinerja Sistem Kontrol Input Mesin Pengupas Kulit Biji Kakao Tipe Piringan Tunggal
Abstrak: Cocoa nutshell peeling procces can use desheller single disc type. The purpose of this study is to modify the input control system of the disc type crusher in order to increasing the work capacity of the machine and maintaning the quality of cocoa nutshell. Auger was used as a metering device to control the amount of cocoa beans that peeled by machine. Auger has 2 cm of inside diameter and 3.5 cm of outside diameter, with 2 types of pitch distance. Design 1 and 2 have a pitch distance of 1.5 and 2 cm, respectively. Performance test was conducted by using 3 kinds of rpm. As the result, the efficiency of the auger type 1 and 2 at 600 rpm; 750 rpm; 900 rpm were; 98.50%; 96.85%; 94.12%, and 96.36%; 90.55%; 89.30%, respectively. The percentages of cocoa beans before modification that didn’t peeled at 600 rpm; 750 rpm; 900 rpm, were 2.16%; 1.98%; 1.95%, and for imperfect peeled at 600 rpm; 750 rpm; 900 rpm were 1.67%; 1.33%; 1.175, and by using auger 1 and 2 the seeds that didn’t peeled, were respectively: 3.44%; 2.43%; 2.32 and 4.48%; 2.85%; 2.47%, and for the seeds that imperfect peeled from auger 1 and 2 were respectively: 2.15%, 1.75%, 1.50% and 2.58%, 1.81%, 1.61%, the yield from auger 1 and 2 were respectively: 83.77%, 82.83%, 82.23% and 83.17%, 82.53%, 82.50%.
Keyword: Bogor Agricultural University (IPB), peeling, cocoa, desheller, bean, auger

Judul: Pengaruh vaksinasi terhadap dinamika populasi pada model SIR (Susceptible-Infected-Recovered)
Abstrak: SIR model can be used to model the spread of diseases in a closed population based on certain assumptions. In this research, the SIR model is formulated by including the factor of vaccination. As the result, the model has been shown to have two equilibrium points, i.e. disease free and endemic equilibrium. A simulation study is carried out to illustrate the model. The results show that some equilibrium points are asymptotically stable. Moreover, a minimum level of vaccination has been defined. For the vaccination level less than the minimum level, increase in the vaccination level results in decrease of the proportion of infected individuals in the corresponding equilibrium point. On the other hand, for the vaccination level greater than the minimum level, increase in the vaccination level results in decrease the proportion of susceptible individuals in the corresponding equilibrium point. Furthermore, when vaccination level is greater than the minimum level, it is found that the time needed for the disease to extinct is shorter.
Keyword: