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%.
Keyword: 

Judul: Karakteristik Biopelet Dari Campuran Serbuk Kayu Sengon Dengan Arang Sekam Padi Sebagai Bahan Bakar Alternatif Terbarukan
Abstrak: Biopellet is one of the alternative fuels which could substitute fossil fuel. The production of biopellet could be made from natural resources based lignocelluloses materials such as albisia sawdust and rice husk charcoal. The objective of this research was to analyze the characteristics of biopellet obtained of the mixture albisia sawdust and rice husk. The compositions of a mixture in this research are as follows 20% : 80%, 40% : 60%, 60% : 40%, 80% : 20%, as well as 100% of albisia sawdust. The test of biopellet included moisture content, density, volatile matters, ash substances, fixed carbon, calorie value and firmness which was based on commercial standard. The result of this research showed that the addition of rice husk charcoal into biopellet derived from albisia sawdust could not only decrease moisture content, but also that addition could increase ash percentages and calorie value. Although there was increasing calorie value, the addition of rice husk charcoal generated the inappropriateness of quality standard for ash percentages. The best quality of biopellet was composed with 100 % albisia sawdust which moisture content, density and calorie value were in accordance with French quality standard (ITEBE).
Keyword: quality standard, rice husk, albisia sawdust, Biopellet

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.
Keyword: