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: Design and Simulation of Hole Making Mechanism on a Precision Palm Fertilizer Machine
Abstrak: Dibeberapa perkebunan kelapa sawit, pemupukan masih dilakukan secara manual. Oleh karena itu, dibutuhkan mesin pemupuk kelapa sawit yang mampu melakukan pemupukan secara efektif dan efisien. Tujuan dari penelitian ini untuk merancang dan mensimulasikan mekanisme pembuat lubang pupuk pada mesin pemupuk kelapa sawit presisi agar lubang pupuk yang dihasilkan presisi secara efektif dan efisien. Penelitian ini dilakukan dengan pendekatan desain fungsional dan struktural yang terdiri dari beberapa tahapan, antara lain: identifikasi dan perumusan masalah, perumusan dan evaluasi konsep desain, analisis desain, gambar teknik, dan simulasi. Desain mekanisme pembuat lubang dirancang menggunakan bantuan software Solidworks 2017 dan EDEM Simulator 2018. Hasil rancangan menghasilkan lubang pupuk dengan diameter lubang 200 mm dengan kedalaman 308 mm. Lengan pembuat lubang dapat memanjang sejauh 875 mm saat aktuator hidrolik 1 ekstrusi maksimal untuk mencapai titik pembuatan lubang pupuk terjauh. Sedangkan komponen pembuat lubang dapat turun sejauh 500 mm saat aktuator hidrolik 2 ekstrusi maksimal untuk melakukan pengeboran lubang pupuk dengan kedalaman 308 mm. Screw yang berfungsi sebagai pembuat lubang juga telah mampu menyalurkan pupuk ke dalam lubang yang telah dihasilkan. Pupuk yang disalurkan memiliki laju aliran massa sebesar 100 gr/s dan debit aliran sebesar 79.37 cm¬3/s., In some oil palm plantations, fertilization is still done manually. Therefore, we need a palm fertilizer machine that is able to fertilize effectively and efficiently. The purpose of this research is to design and simulate the mechanism for making fertilizer holes on a precision oil palm fertilizer machine so that the resulting fertilizer holes are accurately and efficiently produced. This research was conducted with a functional and structural design approach which consists of several stages, including: identification and formulation of problems, formulation and evaluation of design concepts, design analysis, engineering drawings, and simulation. The design of the hole making mechanism was designed using the help of Solidworks 2017 and EDEM Simulator 2018 software. The design results produced a fertilizer hole with a hole diameter of 200 mm with a depth of 308 mm. The hole punch arm can extend as far as 875 mm while the hydraulic actuator 1 extrusion is maximal to reach the furthest point of making the manure hole. Whereas the hole making component can drop as far as 500 mm when the hydraulic actuator 2 extrusion is maximal for drilling fertilizer holes with a depth of 308 mm. The screw that functions as a hole maker has also been able to distribute fertilizer into the holes that have been produced. The distributed fertilizer has a mass flow rate of 100 gr/s and a flow rate of 79.37 cm3/s.
Keyword: hole making arm, hydraulic, manure hole, oil palm, simulation

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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