Judul: Biopelet Kayu Agathis dengan Penguat Kulit Lepasnya
Abstrak: The agathis bark is expected to increase the energy content and durability of the resulting biopellet. The present research was aimed to analyze chemical components of agathis and to determine the quality of agathis wood biopellet fortified with its loosen bark. The klason lignin, extractives, holocellulose and α- cellulose content of wood and bark of the agathis were determined following the standard procedures of TAPPI T 222 0m-88, TAPPI T 204 0m-88, and Browning (1967), respectively. Biopellets of 15 mm diameter were prepared with pelletizing pressure of 1500 psi. The moisture content, ash content, density, durability, and calorific value of the resulting biopellet were compared to those required by DIN EN 14961-2 and 51731 standards. The α-cellulose and holocellulose content of the agathis bark were found lower than these of its wood. However, its klason lignin, extractive, and ash content were higher than these of its wood. The resulting biopellet retained the density of 0.61-0.71 g/cm3, moisture content of 0.42-4.52%, ash content of 0.79-2.73%, durability of 21.26-44.59%, and calorific value of 4524- 4628 kcal/kg. Except for that of the biopellet density and durability, all parameters satisfied the requirements of DIN EN standards. Thermal analysis of biopellet showed that water loss occurred at 36-100 oC and significant mass decomposition between 100 up to 475 oC with the weight loss of 77.34-80.51%. No further decomposition was found at above 480 oC.
Keyword: Bogor Agricultural University (IPB), thermal, bark, biopellet, agathis

Judul: Biopelet: Energi Terbarukan dari Batang Kelapa Sawit
Abstrak: Oil palm trunk (OPT) is a potentional source of biomass for the production of biopellet. In the present research, biopellets were prepared from 25 years old OPT. It was prepared by mixing the meristem part with various percentages of its bark (0, 10, dan 30% bark content). The properties of the resulting biopellet were statistical examined. The durability of biopellet was measured according to ASABE standard procedures and its combustion behavior was examined by thermogravimetry and differential thermal analysis (TG–DTA). The highest biopellet durability was found for biopellet produced at 130 oC pressing temperature with 30% bark content. Scanning electron microscopy (SEM) of pellet of OPT showed the weak of particle bonding due to low of pelletizing pressure. The moisture content, unit density, ash content, and caloric value of pellets were 3.55–5.35%, 525.56–855.23 kg/m3, 2.76–3.44%, dan 17.89–19.14 MJ/kg, respectively. The combustion profiles of biopellet seemed to be unaffected by the bark content on TGA curve. Thermogravimetric analysis on DTA curve indicated that hemicellulose, cellulose, and lignin retained a different pyrolysis characteristic
Keyword: Bogor Agricultural University (IPB), pyrolysis, durability, pellet, Oil palm trunk

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: