Judul: Design Evaluation and Performance of the Bucket Mulcher for the Felling and Shredding of Oil Palm Stems
Abstrak: Replanting activities in oil palm plantations are carried out to replace old and unproductive plants. The purpose of replanting is to increase fruit productivity and also to make the harvest process easier. Replanting methods have been widely developed, including under planting methods and chipping methods. However, with this method a problem arises, namely the development of oil palm stem pests (horn beetles) on the stem after hitting. For this reason, replanting activities require other methods which include the felling and shredding of oil palm trunks. One tool that has been developed for this activity is the Bucket Mulcher tool, which has a dual function, which is to fell trees and shredd oil palm trunks into powder. Palm oil stem powder can be used as mulch in oil palm plantations. This study aims to analyze the design parameters, performance tests, and design evaluations of Bucket Mulcher.The results showed that oil palm plants that are more than 20 years old have an average stem diameter of 0,6 m with a height of 16,02 m. The performance test results show that the best method for felling and shredding oil palm stems is the Push Tree method. Mulcher Bucket Capacity 141,26 kg / minute with 6,02 liters of fuel consumption for each tree. The area of mulch covering the ground is 131,29 m2 with a peak of 0,7 m. Based on the measurement results and technical analysis calculation the diameter of the counter cylinder shaft is 48 mm and uses a rotating belt for transmission with the type T10 with a belt length of 161 cm and a Bucket Mulcher power requirement of 45,76 kW. These data indicate that the Bucket Mulcher is suitable for use but still needs improvement. The wear rate of Bucket Mulcher knife teeth is on average 0,453 grams per hour with material made of Tungsten Carbide. The rate of wear is influenced by silica content, moisture content, and specific gravity of oil palm stems. The Mulcher Bucket Framework uses a Hardox 500 steel plate 11,8 mm thick.
Keyword: Bucket Mulcher, horn beetles, oil palm stems, performance test, and technical analysis

Judul: Kajian Teknik Pengaruh Mulsa Organik Daun Sawit dan Sintetis dan Konsep Rancangan Mesin Pencacah
Abstrak: Mulsa, baik mulsa organik maupun sintetik, dapat meningkatkan pertumbuhan, menjaga kelembaban tanah, dan mencegah pertumbuhan gulma. Daun kelapa sawit merupakan salah satu bahan pendukung yang dapat dijadikan mulsa. Tujuan penelitian ini adalah mendesain mesin pencacah daun kelapa sawit yang kemudian akan mencacah daun untuk dijadikan mulsa. Desain mesin meliputi panjang maksimum daun 1.004 m, lebar maksimum pelepah 0.195 m, dan tinggi pengumpanan mesin 0.952 m. Gaya potong minimum yang harus diberikan pisau 7.00 MPa. Model pisau yang digunakan dalam rancangan adalah pisau pada mesin panen kombinasi. Pisau harus mampu memberikan hasil cacahan sepanjang 6 cm. Mesin pencacah yang didesain memiliki mekanisme pemasukan dan pengeluaran dengan dilengkapi luncuran daun dan pelepah. Penggerak mesin pencacah adalah motor bakar bensin bertenaga 4.8 HP (3.6 kW). Berdasarkan perhitungan penyaluran daya melalui sabuk dan rantai. Sebagai mulsa, daun kelapa sawit memberikan hasil yang baik dalam menjaga kestabilan suhu serta kelembaban tanah. Desain mesin mampu menjadi solusi dalam pemanfaatan limbah daun kelapa sawit….
Keyword: Mulch, Oil Palm Leaves, Design, Chopper, Cutting metode, Uji mulsa lembah sawit, Combine harvester, Analisis rancangan struktural

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.
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