Judul: Design of Rice Husk Biopellet Production Process with a Mixture of Coconut Shell and Sengon Wood Powder
Abstrak: CV Mekar Jaya memiliki limbah dari hasil samping proses penggilingan padi dan belum dimanfaatkan secara maksimal. Oleh sebab itu, dilakukan pemanfaatan limbah sekam padi menjadi biopelet dengan campuran serbuk kayu sengon dan tempurung kelapa. Tujuan dari penelitian ini merancang proses produksi biopelet, mendapatkan formulasi terbaik, menganalisis kualitas, menganalisis kelayakan finansial, dan menganalisis sensitivitas. Metode yang digunakan adalah metode kuantitatif. Penelitian dibagi menjadi beberapa fase, yaitu fase eksplorasi, fase pendefinisian masalah, fase ideasi, fase pengembangan prototipe, dan fase validasi. Formulasi yang digunakan dalam pembuatan biopelet terdiri dari 20% sekam : 80% arang tempurung kelapa, 20% serbuk kayu sengon : 80% arang sekam padi, 20% arang sekam padi : 80% serbuk kayu sengon, dan 20% arang sekam padi : 80% arang tempurung kelapa. Didapatkan formulasi terbaik dari keempat formulasi, yaitu formulasi 20% serbuk kayu sengon : 80% arang sekam. Hasil penelitian berhasil menghasilkan formulasi terbaik, proses produksi dan tata letak produksi yang efisien. Selain itu, hasil perhitungan menghasilkan HPP sebesar Rp 2.127.14/kg dan harga jual sebesar Rp 2.796.75/kg. Hasil analisis kelayakan finansial menunjukkan bahwa rencana pengembangan produk tersebut layak untuk dijalankan dengan nilai NPV sebesar Rp 1.016.463.004, IRR 40,84%, net B/C 1,170 dan PP 3 tahun 5 bulan. Hasil analisis sensitivitas menunjukkan bahwa pada kenaikan harga bahan baku 5% dan 15% menunjukkan hasil yang layak. Namun, dengan kenaikan harga bahan baku sebesar 30% proyek menjadi tidak layak. Hal ini menunjukkan bahwa kenaikan harga bahan baku sebesar 30% akan menyebabkan kerugian dan proyek tidak mencapai tujuan finansial yang diharapkan., CV Mekar Jaya has waste from the by-products of the rice milling process and has not been utilized optimally. Therefore, rice husk waste is used to become biopellets with a mixture of sengon wood powder and coconut shells. The purpose of this study is to design the biopellet production process, obtain the best formulation, analyze quality, analyze financial feasibility, and analyze sensitivity. The method used is a quantitative method. The research is divided into several phases, namely the exploration phase, the problem definition phase, the ideation phase, the prototype development phase, and the validation phase. The formulation used in the manufacture of biopellets consists of 20% husk: 80% coconut shell charcoal, 20% sengon wood powder: 80% rice husk charcoal, 20% rice husk charcoal: 80% sengon wood powder, and 20% rice husk charcoal: 80% coconut shell charcoal. The best formulation of the four formulations was obtained, namely the formulation of 20% sengon wood powder: 80% husk charcoal. The results of the research succeeded in producing the best formulation, efficient production process and production layout. In addition, the results of the calculation resulted in an HPP of Rp 2,127.14/kg and a selling price of Rp 2,796.75/kg. The results of the financial feasibility analysis show that the product development plan is feasible to be implemented with an NPV value of IDR 1,016,463,004, IRR of 40.84%, net B/C of 1,170 and PP of 3 years and 5 months. The results of the sensitivity analysis show that the increase in raw material prices by 5% and 15% shows decent results. However, with a 30% increase in raw material prices, the project
Keyword: biopelet, Formulasi, analisis kelayakan finansial, Analisis sensitivitas

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: Metrik Einstein (Anti-) Self-Dual Berdimensi Empat dengan Metode Cartan
Abstrak: Gravitational field equation can be formulated in differential forms (differential geometry), which describes gravity as a manifestation of the curvature of space-time. Curvature of space-time is characterized by a metric that satisfies the gravitational field equation. With differential forms it can be formulated the (anti-) self-dual Einstein equation, which is a modification of the Cartan structure in (anti-) self-dual basis. Calculation of (anti-) self-dual metric with (anti-) self-dual Einstein equation is simpler than the calculation using Christoffel symbols.
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