Judul: Uji keragaan biopelet dari biomassa limbah sekam padi (Oryza sativa sp.) sebagai bahan bakar alternatif terbarukan
Abstrak: The abundance of rice husks in Indonesia is a potential source of biomass that can be converted into biomass pellet (biopellets). Pelletization can improve the quality and burning characteristic of the biomass. The purpose of this study is to improve the quality of rice husks biopellets by combining the rice husks powders and the rice husks charcoal. Carbonization process was done by using kiln drum whose height is 30 cm and diameter is 19 cm for ±5 hours at a temperature of 400 0C. The percentage of rice husks charcoal used was 0%, 10%, and 20%. Densification process was done by pellet mill whose capacity is 300 kg/h with a dies diameter of 8 mm. Used cooking oil was added to the raw material for 4.77% w/w. Biopellets was sun-dried for 4 hours. Then, the physico-chemical properties and the combustion characteristics were tested. Mass and energy flows were measured by using method of input-output analysis for the biopellets production process. The results of this research showed that the addition of rice husk charcoal into the rice husk biopellet generated a different effect significantly to the moisture content, ash content, volatile matter, bulk density, and the heating value of rice husks biopellet, but there was no significant effect to the level of fixed carbon, firmness, consumption rate, and the efficiency of combustion. Based on the physico-chemical properties and the combustion characteristics, rice husk biopellets that contained 10% of husk charcoal has the best quality. It has 3.60 % of moisture content, 17.47% of ash content, 72.86% of volatile matter, 9.68% of fixed carbon, and 728.43 kg/m3 of bulk density. The heating value of the biopellets was 4329.63 kcal/kg, while the firmness was 10.54 kg/cm2. In addition, the consumption rate of the biopellets was 1.84 kg/h while the efficiency of combustion was 8.34%. The production of rice husk biopellets on a laboratory scale produced yield of 18.67%. Biopellets increased the heating value of ricu husk for 25.49%.
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Judul: Study of Biopellet Formulation Based on Albasia Wood Powder with a Mixture of Straw and Rice Husk Charcoal
Abstrak: Serbuk kayu albasia dan limbah padi merupakan salah satu sumber bahan bakar alternatif potensial berasal dari biomassa yang dapat dimanfaatkan menjadi biopelet sebagai solusi pemanfaatan limbah. Tujuan penelitian ini adalah menganalisis dan mengetahui karakteristik biopelet berbahan dasar serbuk kayu albasia dengan campuran jerami dan arang sekam serta mengetahui komposisi formulasi terbaik dari bahan dasar biopelet tersebut sebagai energi bahan bakar alternatif. Pembuatan biopelet menggunakan pelletizer tipe fixed dies dengan perbandingan formulasi bahan baku yaitu A0 (arang sekam 90% : perekat 10%), A1 (jerami padi 90% : perekat 10%), A2 (serbuk kayu albasia 90% : perekat 10%), A3 (serbuk kayu albasia 25% : jerami 25% : arang sekam 40% perekat 10%), A4 (serbuk kayu albasia 25% : jerami 40% : arang sekam 25% : perekat 10%), dan A5 (serbuk kayu albasia 40% : jerami 25% : arang sekam 25% : perekat 10%). Perlakuan terbaik biopelet diperoleh pada komposisi serbuk kayu albasia 90% dan perekat 10% berdasarkan nilai kadar air 10,62%, kadar abu 1,83%, dan kerapatan apparent 0,725 g/cm3 yang memenuhi standar SNI 8675:2018. Nilai kalor dari biopelet tersebut yaitu 17,16 MJ/kg., Albasia sawdust and rice waste are potential alternative fuel sources derived from biomass that can be used as biopellets as a solution for waste utilization. The purpose of this study was to analyze and determine the characteristics of biopellets made from albasia wood powder with a mixture of straw and husk charcoal and to determine the composition of the best formulation of these biopellets as alternative fuel energy. Making biopellets using a fixed dies type pelletizer with a ratio of raw material formulations, namely A0 (90% husk charcoal : 10% adhesive), A1 (90% rice straw : 10% adhesive), A2 (90% albasia wood powder : 10% adhesive), A3 (25% albasia wood powder : 25% straw : 40% husk charcoal : 10% adhesive), A4 (25% albasia wood powder : 40% straw : 25% husk charcoal : 10% adhesive), and A5 (40% albasia wood powder : 25% straw : 25% husk charcoal : 10% adhesive). The best treatment for biopellet was obtained at the composition of 90% albasia wood powder and 10% adhesive based on the value of water content of 10,62%, ash content of 1,83%, and apparent density of 0,725 g/cm3 which meet the standards of SNI 8675:2018. The calorific value of the biopellet is 17,16 MJ/kg.
Keyword: albasia sawdust, biopellet, fixed dies pelletizer, husk charcoal, rice straw

Judul: Tinjauan Matematis pada Model Makroskopik dan Mikroskopik Arus Lalu-lintas
Abstrak: Traffic flow phenomenon can be described through mathematical model such as continuous dynamic model with an ordinary differential equation so that it can be solved with integral factors. In this paper three simple models of traffic flow are discussed, i.e, two macroscopic and one microscopic models. Macroscopic model formulates dynamics of the traffic flow that occurs on a large number of vehicles on a road. While the microscopic model explains drivers’ behavior in their interaction with other vehicles ahead, i.e, car-following model. This paper shows the existence of ordinary differential equation found in the traffic flow model and indicates some different representations in the context of the same model. It also reviews a simple model of traffic flow along a single link, which leads to some unexpected results, i.e, it can express the solution model in term of link outflows as well as trip time. In the microscopic model, simulation is done to illustrate the behavior of the drivers with a sensitivity coefficient as a benchmark parameter.
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