Judul: Determination of Grass Waste Biopellet Formulation with West Indian Elm Sawdust Mixture (Guazuma ulmifolia)
Abstrak: Limbah rerumputan dan serbuk kayu jati belanda berpotensi sebagai sumber energi berkelanjutan untuk memenuhi kebutuhan energi yang kian meningkat. Salah satu sumber energi tersebut adalah bahan bakar padat berupa biopelet. Penelitian ini bertujuan untuk menentukan formulasi bioepelet terbaik dari campuran limbah rerumputan dan serbuk kayu jati belanda. Pembuatan biopelet limbah rerumputan dan serbuk kayu jati belanda menggunakan pelletizer tipe rotary dies dengan perbandingan formulasi diantaranya A1 (100% limbah rerumputan), A2 (70% limbah rerumputan : 30% serbuk kayu jati belanda), A3 (65% limbah rerumputan : 35% serbuk kayu jati belanda), A4 (60% limbah rerumputan : 40% serbuk kayu jati belanda), A5 (55% limbah rerumputan : 45% serbuk kayu jati belanda), A6 (50% limbah rerumputan : 50% serbuk kayu jati belanda), dan AN (100% serbuk kayu jati belanda). Formulasi campuran terbaik terdapat pada formulasi A3, yaitu dengan komposisi 65% limbah rerumputan dan 35% sebuk kayu jati belanda. Pemilihan formulasi terbaik didasarkan pada standar SNI 86752018 meliputi nilai kalor yang tinggi sebesar 17,76 MJ/kg, kadar air yang rendah sebesar 4,24%, kerapatan bahan sebesar 0,61 g/cm3, ketahanan sebesar 95,76%, kadar abu sebesar 6,54%, kadar zat terbang sebesar 72,38% dan laju pembakaran sebesar 2,58 kg/jam., Waste grass and west Indian elm sawdust have the potential as a source of sustainable energy to meet the increasing energy needs. One of these energy sources is solid fuel in the form of biopellets. This study aims to determine the best biopellet formulation from a mixture of grass waste and west Indian elm sawdust. Making biopellet from grass waste and west Indian elm sawdust using rotary dies pelletizer with a formulation ratio including A1 (100% grass waste), A2 (70% grass waste : 30% west Indian elm sawdust), A3 (65% grass waste : 35% west Indian elm sawdust), A4 (60% grass waste: 40 % west Indian elm sawdust), A5 (55% grass waste : 45% west Indian elm sawdust), A6 (50% grass waste : 50% west Indian elm sawdust), and AN (100% west Indian elm sawdust). The best mixed formulation is found in the A3 formulation, which is with a composition of 65% grass waste and 35% west Indian elm sawdust. Selection of the best formulation is based on the SNI 8675-2018 standard includes high calorific value of 17.76 MJ/kg, low moisture content of 4.24%, material density of 0.61 g/cm3, resistance of 95.76%, ash content of 6.54%, volatile matter content of 72.38% and combustion rate of 2.58 kg/hour.
Keyword: biopelet, limbah rerumputan, serbuk kayu jati belanda, pelletizer tipe rotary dies

Judul: Karakteristik Biopelet Limbah Ampas Tebu dan Batang Singkong
Abstrak: Limbah ampas tebu (bagasse) dan batang singkong merupakan biomassa yang berpotensi menjadi alternatif bahan bakar terbarukan untuk memenuhi kebutuhan energi yang kian meningkat. Penelitian ini bertujuan untuk menganalisis karakteristik biopelet dan menentukan formulasi biopelet terbaik dari campuran limbah ampas tebu dan batang singkong. Pembuatan biopelet menggunakan pelletizer tipe rotary dies dengan perbandingan komposisi bahan baku yaitu A1 (100% serbuk batang singkong), A2 (100% limbah ampas tebu), A3 (20% limbah ampas tebu : 80% serbuk batang singkong), A4 (80% limbah ampas tebu : 20% serbuk batang singkong), A5 (50% limbah ampas tebu : 50% serbuk batang singkong), A6 (65% limbah ampas tebu : 35% serbuk batang singkong), A7 (35% limbah ampas tebu: 65% serbuk batang singkong). Penentuan biopelet terbaik berdasarkan pembobotan dengan tingkat kepentingan parameter dengan bobot tertinggi hingga terendah yaitu nilai kalor, kadar abu, kadar zat terbang, kerapatan, kadar air, dan laju pembakaran. Formulasi terbaik dari campuran kedua bahan baku berdasarkan SNI 8675-2018 didapatkan dari perlakuan A5 dengan rata-rata hasil uji kerapatan sebesar 0,60 g/cm³, kadar air 8,29%, kadar zat terbang 77,63%, kadar abu 4,10%, kadar karbon terikat 9,98%, nilai kalor 17,40 MJ/kg, keteguhan 96,55%, laju pembakaran 3,57 kg/jam, serta suhu pembakaran 761°C., Sugarcane bagasse and cassava stems are biomass waste which have potential as alternative renewable fuels by converting it into biopellets. This research aims to analyze the characteristics of biopellets made from a mixture of sugarcane bagasse and cassava stems waste, and determine the best formulation based on SNI no 8765-2018. A rotary dies type pelletizer has been used to produce the pellets. Pellets formulation was represented by the ratio of raw material composition, they were A1 (100% cassava stem powder), A2 (100% sugarcane bagasse waste), A3 (20% sugarcane bagasse waste : 80% cassava stem powder), A4 (80% bagasse waste : 20% cassava stem powder), A5 (50% sugarcane bagasse waste : 50% cassava stem powder), A6 (65% sugarcane bagasse waste : 35% cassava stem powder), A7 (35% sugarcane bagasse waste : 65 % cassava stem powder). Determination of the best biopellets is based on the scoring with the level of lightness of the parameters with the highest to lowest score is calorific value, ash content, volatile matter content, density, moisture content, and combustion rate. The best formulation obtained from A5 composition (50% bagasse and 50% cassava stem) with average density of 0,60 g/cm³, water content of 8,29%, volatile matter content of 77,63%, ash content of 4,10%, bound carbon content of 9,98%, calorific value 17,40 MJ/kg, durability 96,55%, and combustion rate 3,67 kg/hour, combustion temperature 761°C.
Keyword: biomassa, biopelet, bagasse, batang singkong, pelletizer

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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